code: добавил параметр prompt

project/main.cpp

@@ -13,9 +13,10 @@ struct Input
 };
 
 Input
-input_data(istream& in)
+input_data(istream& in, bool prompt)
 {
     size_t number_count;
+    if (prompt)
     cerr << "Enter number count: ";
     in >> number_count;
 
@@ -34,7 +35,7 @@ input_data(istream& in)
 
 int main()
 {
-    auto in = input_data(cin);
+    auto in = input_data(cin, true);
     auto bins = make_histogram(in.numbers, in.bin_count);
     show_histogram_svg(bins);
     getch();