/in/foo.c: In function 'main':
/in/foo.c:6:10: warning: unused variable 'a' [-Wunused-variable]
  int i=0,a;
          ^
/in/foo.c: At top level:
/in/foo.c:20:2: error: expected identifier or '(' before 'return'
  return 0;
  ^~~~~~
/in/foo.c:21:1: error: expected identifier or '(' before '}' token
 }
 ^