foo.cc: In function 'int main()':
foo.cc:19:15: warning: unused variable 'j' [-Wunused-variable]
   19 |         int n,j,m;
      |               ^
foo.cc:31:23: warning: 'm' may be used uninitialized [-Wmaybe-uninitialized]
   31 |                 cout<<m<<endl;
      |                       ^
foo.cc:19:17: note: 'm' was declared here
   19 |         int n,j,m;
      |                 ^