/in/foo.c: In function 'main':
/in/foo.c:12:12: error: 'sum' undeclared (first use in this function)
   12 |         if(sum==i){
      |            ^~~
/in/foo.c:12:12: note: each undeclared identifier is reported only once for each function it appears in
/in/foo.c:12:17: error: 'i' undeclared (first use in this function)
   12 |         if(sum==i){
      |                 ^
/in/foo.c: At top level:
/in/foo.c:16:7: error: expected identifier or '(' before 'return'
   16 |       return 0;
      |       ^~~~~~
/in/foo.c:17:1: error: expected identifier or '(' before '}' token
   17 | }
      | ^