diff --git a/main.cpp b/main.cpp
index ec2eb96..394310e 100644
--- a/main.cpp
+++ b/main.cpp
@@ -11,25 +11,34 @@ struct Input
     size_t bin_count{};
 };
 
-Input input_data()
+Input input_data(istream& in, bool prompt)
 {
     size_t number_count;
-    cerr << "Number count: ";
-    cin >> number_count;
-    Input in;
-    in.numbers.resize(number_count);
+    if (prompt) {
+        cerr << "Number count: ";
+    }
+    in >> number_count;
+
+    Input input;
+    input.numbers.resize(number_count);
 
-    cerr << "Numbers: ";
+    if (prompt) {
+        cerr << "Numbers: ";
+    }
     for (size_t i = 0; i < number_count; i++) {
-        cin >> in.numbers[i];
+        in >> input.numbers[i];
     }
-    cerr << "Enter bin count:";
-    cin >> in.bin_count;
-    return in;
+
+    if (prompt) {
+        cerr << "Enter bin count: ";
+    }
+    in >> input.bin_count;
+
+    return input;
 }
 
 int main() {
-    auto in = input_data();
+    auto in = input_data(cin, true);
     auto bins = make_histogram(in.numbers, in.bin_count);
     show_histogram_svg(bins);
     return 0;