diff --git a/CHANGES.md b/CHANGES.md
new file mode 100644
index 0000000..2d1731f
--- /dev/null
+++ b/CHANGES.md
@@ -0,0 +1,22 @@
+# Backend internal interview (rust)
+
+## CHANGES: fixed branch
+
+- Moving from **HashMap** to **BTreeMap** to preseve loading lines order.
+- Fix **lines parser** in Maps **metrics** and in **aggregated_metrics** to be handled properly.
+- Fix **unwrap / expect** for obvious reasons, add simple error message via **map_err**, **unwrap_or_else** and **closure function**.
+- Fix some source code lines order, output format and conversions.
+- Change some **iterators** to <u>functional mode</u>.
+- Separate tasks to independent funtions for better isolation, less responsibilities and help on **tests** handling.
+- Adding **output_path** to help on result output options.
+- Following **unit tests** are implemented:
+  - <u>test_load_input</u> test load input file **input.txt**.
+  - <u>test_invalid_line_value</u> test use invalid value in line parsing.
+  - <u>test_invalid_line</u> test use invlid value in line parsing.
+  - <u>test_expected_metrics</u> test load input data from **input.txt** compare with **output_expected.txt**.
+  
+> Code simply **works as expected**
+> It is not be able to **process multiple metrics in parallel** yet.
+> A full refactoring has to be done for <u>better quality, maintenance and be more readable</u>. (Structs, implementaitions, settings for multiple inputs, etc).
+
+Next round in: [Improve branch](/NewRelic/be-technical-interview-rust/src/branch/improved)
diff --git a/README.md b/README.md
index 76b6c56..3f2fcb9 100644
--- a/README.md
+++ b/README.md
@@ -1,4 +1,10 @@
-# Backend internal interview (rust)
+# Backend internal interview (rust) - basic-fixed  
+
+> Code simply **works as expected**
+> It is not be able to **process multiple metrics in parallel** yet.
+> A full refactoring has to be done for <u>better quality, maintenance and be more readable</u>. (Structs, implementaitions, settings for multiple inputs, etc).
+
+See [main chainges](CHAINGES.md)
 
 A **Refactor metric-consumer** task
 
diff --git a/src/main.rs b/src/main.rs
index f48b5a1..1904eb9 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -1,76 +1,168 @@
-use std::collections::HashMap;
+use std::{collections::BTreeMap, process::exit};
 use std::error::Error;
 use std::fs::File;
 use std::io::Read;
-use std::time::{Duration, UNIX_EPOCH};
+use std::time::{SystemTime,Duration, UNIX_EPOCH};
+use chrono::{DateTime,Utc};
+use regex::Regex;
 
 fn parse(
-    file: File,
-) -> Result<HashMap<String, HashMap<std::time::SystemTime, f64>>, Box<dyn Error>> {
-    let mut file = file;
+    mut file: File,
+) -> Result<BTreeMap<String, BTreeMap<SystemTime, f64>>, Box<dyn Error>> {
     let mut contents = String::new();
     file.read_to_string(&mut contents)?;
+    let re = regex::Regex::new(r"(\d+) (\w+) (\d+)")?; 
+    Ok(parse_content(contents, re))
+}
+fn parse_content(
+    contents: String,
+    re: Regex,
+) -> BTreeMap<String, BTreeMap<SystemTime, f64>> {
+    dbg!(&contents);
+    let mut metrics: BTreeMap<String, BTreeMap<SystemTime, Vec<f64>>> = BTreeMap::new();
+    let show_invalid_line = | index: usize, line: &str | println!("invalid line: {} {}", index, line);
 
-    let mut metrics: HashMap<String, HashMap<std::time::SystemTime, Vec<f64>>> = HashMap::new();
-
-    for line in contents.lines() {
-        let re = regex::Regex::new(r"(\d+) (\w+) (\d+)").unwrap();
+    for (index,line ) in contents.lines().enumerate() {
         if let Some(caps) = re.captures(line) {
             let timestamp_raw = &caps[1];
             let metric_name = &caps[2];
             let metric_value_raw = &caps[3];
-
-            let timestamp = timestamp_raw.parse::<i64>().unwrap();
-            let metric_value = metric_value_raw.parse::<f64>().unwrap();
-
-            if !metrics.contains_key(metric_name) {
-                metrics.insert(metric_name.to_string(), HashMap::new());
-            }
-
+            let timestamp = timestamp_raw.parse::<i64>().unwrap_or_else(|e|{
+                println!("Parse timestamp {} error {}",timestamp_raw,e);
+                0
+            });
+            if timestamp == 0 {
+                show_invalid_line(index, line);
+                continue;
+            } 
+            let metric_value = metric_value_raw.parse::<f64>().unwrap_or_else(|e|{
+                println!("Parse metric_value {} error {}",metric_value_raw,e);
+                0 as f64
+            });
+            if metric_value == 0 as f64 { 
+                show_invalid_line(index, line);
+                continue;
+            } 
             let minute = UNIX_EPOCH + Duration::from_secs((timestamp - (timestamp % 60)) as u64);
-            metrics
-                .get_mut(metric_name)
-                .unwrap()
-                .insert(minute, vec![metric_value]);
-        } else {
-            println!("invalid line");
-        }
-    }
-
-    let mut aggregated_metrics: HashMap<String, HashMap<std::time::SystemTime, f64>> =
-        HashMap::new();
-
-    for (metric_name, time_val_list) in metrics {
-        aggregated_metrics.insert(metric_name.clone(), HashMap::new());
-
-        for (time, values) in time_val_list {
-            let mut sum = 0.0;
-            for v in values.iter() {
-                sum += *v
+            if let Some(metric) =  metrics.get_mut(metric_name) {
+                if let Some(metric_data) = metric.get_mut(&minute) {
+                    metric_data.push(metric_value); 
+                } else {
+                    metric.insert(minute, vec![metric_value]); 
+                }
+            } else {
+                let metric_time: BTreeMap <SystemTime, Vec<f64>> =  [(minute, vec![metric_value])].into_iter().collect();
+                metrics.entry(metric_name.to_string()).or_insert( metric_time);
             }
-            let average = sum / values.len() as f64;
-
-            aggregated_metrics
-                .get_mut(&metric_name)
-                .unwrap()
-                .insert(time, average);
+        } else {
+            show_invalid_line(index, line);
         }
     }
 
-    Ok(aggregated_metrics)
+    let mut aggregated_metrics: BTreeMap<String, BTreeMap<SystemTime, f64>> = BTreeMap::new();
+    metrics.into_iter().for_each(|(metric_name, time_val_list)| {
+        time_val_list.into_iter().for_each(|(time, values)| {
+            let average = values.iter().sum::<f64>() / values.len() as f64;
+            if let Some(metric) =  aggregated_metrics.get_mut(&metric_name) {
+                if let Some(metric_data) = metric.get_mut(&time) {
+                    *metric_data = average;
+                } else {
+                    metric.insert(time, average); 
+                }
+            } else {
+                let metric_time: BTreeMap <SystemTime,f64> =  [(time, average)].into_iter().collect();
+                aggregated_metrics.entry(metric_name.to_string()).or_insert( metric_time);
+            }
+        })
+    });
+    aggregated_metrics
 }
 
+fn load_input(file_path: &str) -> Result<BTreeMap<String, BTreeMap<SystemTime, f64>>, Box<dyn Error>> {
+    let file = File::open(&file_path)
+        .map_err(|err| format!("Error reading file: {} {}", &file_path, err))?;
+    let metrics = parse(file)
+        .map_err(|err| format!("Unable to parse: {} {}", &file_path, err))?;
+    Ok(metrics)
+}
+fn show_metrics(metrics: BTreeMap<String, BTreeMap<SystemTime, f64>>, output_path: &str) -> Vec<String> {
+    let mut output = Vec::new();
+    metrics.into_iter().for_each(|(metric_name, time_val)| 
+            for (time, value) in time_val {
+                let output_line = format!(
+                    "{} {} {:?}",
+                    DateTime::<Utc>::from(time).format("%Y-%m-%dT%H:%M:%SZ"),
+                    metric_name,
+                    value
+                );
+                match output_path {
+                    "vec" => output.push(output_line),
+                    "print" | _  => println!("{}", output_line), 
+                }
+            }
+    );
+    output
+}
 fn main() {
-    let file = File::open("input.txt").expect("Unable to open file");
-    let metrics = parse(file).expect("Unable to parse file");
-    for (metric_name, time_val) in metrics {
-        for (time, value) in time_val {
-            println!(
-                "{} {:?} {:.2}",
-                metric_name,
-                chrono::DateTime::<chrono::Utc>::from(time),
-                value
-            );
+    let default_input = String::from("input.txt");
+    match load_input(&default_input) {
+        Ok(metrics) => {
+            let _ = show_metrics(metrics, "");
+        },
+        Err(err) => {
+            eprint!("Error: {}", err);
+            exit(1);
         }
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    #[test]
+    fn test_load_input() -> Result<(), String>{
+        let default_input = String::from("input.txt");
+        match load_input(&default_input) {
+            Ok(_) => Ok(()),
+            Err(e) => Err(format!("Error: {}",e).into()),
+        }
+    }
+    #[test]
+    fn test_invalid_line_value() -> Result<(), String>{
+        let contents = String::from("1650973075 cpu A47\n");
+        let re = regex::Regex::new(r"(\d+) (\w+) (\d+)")
+            .map_err(|err| format!("Error regex: {}", err))?;
+        let result = parse_content(contents.clone(), re);
+        if result.len() == 0 {
+            Ok(())
+        } else {
+            Err(format!("Error invalid line value: {}", contents).into())
+        }
+    }
+        #[test]
+    fn test_invalid_line_time() -> Result<(), String>{
+        let contents = String::from("1650973075A cpu 47\n");
+        let re = regex::Regex::new(r"(\d+) (\w+) (\d+)")
+            .map_err(|err| format!("Error regex: {}", err))?;
+        let result = parse_content(contents.clone(), re);
+        if result.len() == 0 {
+            Ok(())
+        } else {
+            Err(format!("Error invalid line time: {}", contents).into())
+        }
+    }
+    #[test]
+    fn test_expected_metrics() {
+        use std::io::{prelude::*, BufReader};
+        let default_input = String::from("input.txt");
+        let metrics = load_input(&default_input).unwrap_or_default();
+        let data_metrics = show_metrics(metrics, "vec");
+
+        let expected_output = String::from("output_expected.txt");
+        let file = File::open(expected_output.clone()).expect(format!("no such file: {}", expected_output).as_str());
+        let buf = BufReader::new(file);
+        let lines: Vec<String> = buf.lines().map(|l| l.expect("Could not parse line")).collect();
+
+        assert_eq!(lines.join("\n"),data_metrics.join("\n"));
+    }
+}
\ No newline at end of file