diff --git a/brc.exs b/brc.exs
index 7df0fbe..7c10e74 100644
--- a/brc.exs
+++ b/brc.exs
@@ -7,7 +7,38 @@ defmodule Brc do
   require Logger
 
   def run(path) do
-    for {city, [min, max, mean]} <- parse_file(path) do
+    compute_file(path)
+    |> output_results()
+  end
+
+  def compute_file(path) do
+    Logger.info("computing from file #{path}")
+
+    File.stream!(path)
+    |> Flow.from_enumerable()
+    |> Flow.map(&parse_line/1)
+    |> Flow.partition(key: {:elem, 0})
+    |> Flow.reduce(fn -> %{} end, &update_city_temp_map/2)
+  end
+
+  def update_city_temp_map({city, temp}, acc) do
+    Map.update(acc, city, [temp, temp, temp],
+      fn [prev_min, prev_max, mean] ->
+        [
+          min(prev_min, temp),
+          max(prev_max, temp),
+          (mean + temp) / 2
+        ]
+      end)
+  end
+
+  def parse_line(line) do
+    [city, temp_text] = String.trim(line) |> String.split(";")
+    {city, String.to_float(temp_text)}
+  end
+
+  def output_results(results) do
+    for {city, [min, max, mean]} <- results do
       "#{city}=#{min}/#{max}/#{Float.round(mean, 1)}"
     end
     |> Enum.sort(Cldr.Collation)
@@ -15,25 +46,7 @@ defmodule Brc do
     |> then(fn out -> "{" <> out <> "}" end)
     |> IO.puts()
   end
-
-  def parse_file(path) do
-    Logger.info("parse file #{path}")
-
-    File.stream!(path)
-    |> Flow.from_enumerable()
-    |> Flow.map(&parse_line/1)
-    |> Flow.partition()
-    |> Flow.reduce(fn -> %{} end, fn {city, temp}, acc ->
-      Map.update(acc, city, [temp, temp, temp], fn [prev_min, prev_max, mean] ->
-        [min(prev_min, temp), max(prev_max, temp), (mean + temp) / 2]
-      end)
-    end)
-  end
-
-  def parse_line(line) do
-    [city, temp] = String.trim(line) |> String.split(";")
-    {city, String.to_float(temp)}
-  end
 end
 
-Brc.run("./measurements.txt")
+{path, _} = System.argv() |> List.pop_at(0, "./measurements.txt")
+Brc.run(path)