/in/foo.c:2:1: warning: data definition has no type or storage class
 n=int(input())
 ^
/in/foo.c:2:1: warning: type defaults to 'int' in declaration of 'n' [-Wimplicit-int]
/in/foo.c:2:3: error: expected expression before 'int'
 n=int(input())
   ^~~