foo.c:10:12: error: expected declaration specifiers or ‘...’ before string constant
   10 |     printf("%d", x, sum);
      |            ^~~~
foo.c:10:18: error: unknown type name ‘x’
   10 |     printf("%d", x, sum);
      |                  ^
foo.c:10:21: error: unknown type name ‘sum’
   10 |     printf("%d", x, sum);
      |                     ^~~
foo.c:11:5: error: expected identifier or ‘(’ before ‘return’
   11 |     return 0;
      |     ^~~~~~
foo.c:12:1: error: expected identifier or ‘(’ before ‘}’ token
   12 | }
      | ^