/in/foo.cc: In function 'int main(int, char**)':
/in/foo.cc:45:6: warning: unused variable 'cnt1' [-Wunused-variable]
  int cnt1 = 0;
      ^~~~
/in/foo.cc:46:6: warning: unused variable 'cnt2' [-Wunused-variable]
  int cnt2 = 0;
      ^~~~
/in/foo.cc:47:6: warning: unused variable 'cnt3' [-Wunused-variable]
  int cnt3 = 0;
      ^~~~