diff --git a/nice-project/ImportantStuff.cs b/nice-project/ImportantStuff.cs
index 1c77ade..e945038 100644
--- a/nice-project/ImportantStuff.cs
+++ b/nice-project/ImportantStuff.cs
@@ -16,13 +16,7 @@ public int DoWhatNeedsToBeDone(IFileReader fileReader)
 
         private int CalculateSumOf(IEnumerable<int> allNumbers)
         {
-            var sum = 0;
-            foreach (var number in allNumbers)
-            {
-                sum += number;
-            }
-
-            return sum;
+            return allNumbers.Sum();
         }
     }
 }
\ No newline at end of file
diff --git a/nice-project/Program.cs b/nice-project/Program.cs
index 0f4c8c4..f3873a9 100644
--- a/nice-project/Program.cs
+++ b/nice-project/Program.cs
@@ -14,6 +14,9 @@ static void Main(string[] args)
             var result = stuff.DoWhatNeedsToBeDone(fileReader);
             
             Console.WriteLine($"Result is {result}");
+            
+            // Wait for input
+            Console.ReadLine();
         }
     }
 }
\ No newline at end of file
diff --git a/nice-project/SomeStrangeFileReader.cs b/nice-project/SomeStrangeFileReader.cs
new file mode 100644
index 0000000..30cfa05
--- /dev/null
+++ b/nice-project/SomeStrangeFileReader.cs
@@ -0,0 +1,21 @@
+namespace NiceProject
+{
+    using System.Collections.Generic;
+    using System.IO;
+
+    public class SomeStrangeFileReader : IFileReader
+    {
+        private string path;
+        
+        public SomeStrangeFileReader(string path)
+        {
+            this.path = path;
+        }
+
+        public IEnumerable<int> ReadAllNumbers()
+        {
+            FileInfo fi = new FileInfo(path);
+            yield return (int) fi.Length;
+        }
+    }
+}
\ No newline at end of file