foo.c:1:1: warning: data definition has no type or storage class
    1 | num = int(input())
      | ^~~
foo.c:1:1: error: type defaults to ‘int’ in declaration of ‘num’ [-Wimplicit-int]
foo.c:1:7: error: expected expression before ‘int’
    1 | num = int(input())
      |       ^~~