/in/foo.cc: In function 'int main()':
/in/foo.cc:14:15: warning: 'sum' may be used uninitialized [-Wmaybe-uninitialized]
   14 |         cout<<sum;
      |               ^~~
/in/foo.cc:5:15: note: 'sum' was declared here
    5 |         int n,sum;
      |               ^~~