/in/foo.c:3:1: warning: data definition has no type or storage class
 m=float(input('公里数:'))
 ^
/in/foo.c:3:1: warning: type defaults to 'int' in declaration of 'm' [-Wimplicit-int]
/in/foo.c:3:3: error: expected expression before 'float'
 m=float(input('公里数:'))
   ^~~~~
/in/foo.c:3:15: warning: character constant too long for its type
 m=float(input('公里数:'))
               ^~~~~~~~~~~~