/in/foo.c:10:8: error: expected declaration specifiers or '...' before string constant
 printf("%d\n",sum);
        ^~~~~~
/in/foo.c:10:15: error: unknown type name 'sum'
 printf("%d\n",sum);
               ^~~
/in/foo.c:11:1: error: expected identifier or '(' before 'return'
 return 0;
 ^~~~~~