diff --git a/main.cpp b/main.cpp
index 8c2000b..1c98e8f 100644
--- a/main.cpp
+++ b/main.cpp
@@ -12,25 +12,25 @@ struct Input
 };
 
 Input
-input_data()
+input_data(istream& stream)
 {
     size_t number_count;
     cerr << "Enter number count: ";
-    cin >> number_count;
+    stream >> number_count;
     Input in;
     in.numbers.resize(number_count);
     for (size_t i = 0; i < number_count; i++)
     {
-        cin >> in.numbers[i];
+        stream >> in.numbers[i];
     }
     cerr << "Enter bin count: ";
-    cin >> in.bin_count;
+    stream >> in.bin_count;
     return in;
 }
 
 int main()
 {
-    Input in = input_data();
+    Input in = input_data(cin);
     vector<size_t> bins = make_histogram(in.numbers, in.bin_count);
     show_histogram_svg(bins);
 }