/in/foo.c:1:1: warning: data definition has no type or storage class
 a = float(input())
 ^
/in/foo.c:1:1: warning: type defaults to 'int' in declaration of 'a' [-Wimplicit-int]
/in/foo.c:1:5: error: expected expression before 'float'
 a = float(input())
     ^~~~~