/in/foo.cc: In function 'int main()':
/in/foo.cc:47:15: warning: unused variable 'u' [-Wunused-variable]
   47 |     int i, j, u, v;
      |               ^
/in/foo.cc:47:18: warning: unused variable 'v' [-Wunused-variable]
   47 |     int i, j, u, v;
      |                  ^