foo.c:1:1: warning: data definition has no type or storage class
    1 | num=input()
      | ^~~
foo.c:1:1: warning: type defaults to ‘int’ in declaration of ‘num’ [-Wimplicit-int]
foo.c:1:5: warning: implicit declaration of function ‘input’ [-Wimplicit-function-declaration]
    1 | num=input()
      |     ^~~~~
foo.c:1:5: error: initializer element is not constant
foo.c:2:1: error: expected ‘,’ or ‘;’ before ‘num’
    2 | num=int(num)
      | ^~~