diff --git a/main.cpp b/main.cpp
index 1d7ec2d..b5bd8ec 100644
--- a/main.cpp
+++ b/main.cpp
@@ -13,11 +13,11 @@ using namespace std;
     };
 
 Input
-input_data()
+input_data(istream& tin)
 {
     size_t n;
     cerr<<"Marks: ";
-    cin>>n;
+    tin>>n;
 
     Input in;
     in.A.resize(n);
@@ -28,13 +28,13 @@ input_data()
     }
 
     cerr<<"Rows: ";
-    cin>>in.bin;
+    tin>>in.bin;
     return in;
 }
 
 int main()
 {
-    Input in = input_data();
+    auto in = input_data(cin);
     auto B = make_histogram(in.A, in.bin);
     show_histogram_svg (B);