/in/foo.cc: In function 'int main()':
/in/foo.cc:11:15: warning: 'a' may be used uninitialized [-Wmaybe-uninitialized]
   11 |         cout<<a;
      |               ^
/in/foo.cc:5:17: note: 'a' was declared here
    5 |         int m,n,a;
      |                 ^