计算火车运行时间 (15分)

#include<stdio.h>
#include<math.h>
main()
{
    int a,b,c,d,e,f,g,h;
    scanf("%d %d",&a,&b);
    e=a/100;
    f=b/100;
    g=a-100*e;
    h=b-100*f;
    c=f-e;
    d=h-g;
    if(d<0){
    c=c-1;
    d=d+60;}
    printf("%02d:%02d\n",c,d);
    
}