/in/foo.cc: In function 'int main()':
/in/foo.cc:12:12: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
   cin >> a + 1;  
          ~~^~~
/in/foo.cc:15:3: warning: this 'for' clause does not guard... [-Wmisleading-indentation]
   for ( int i = 1; i <= n; i++ )
   ^~~
/in/foo.cc:26:5: note: ...this statement, but the latter is misleadingly indented as if it is guarded by the 'for'
     printf("%d",n-f[n][n]);
     ^~~~~~