/in/foo.cc: In function 'int main()':
/in/foo.cc:17:15: warning: unused variable 'left' [-Wunused-variable]
   17 |     int n, m, left, right, time;
      |               ^~~~
/in/foo.cc:17:21: warning: unused variable 'right' [-Wunused-variable]
   17 |     int n, m, left, right, time;
      |                     ^~~~~