#include<stdio.h>
#include<iostream>
using namespace std;

int main()
{
    int s1,f1,m1;
    int s2,f2,m2;
    int s,f,m;

    scanf("%d:%d:%d",&s1,&f1,&m1);
    scanf("%d:%d:%d",&s2,&f2,&m2);
    int time1 = s1*60*60 + f1*60 + m1;
    int time2 = s2*60*60 + f2*60 + m2;
    int time;
    if(time2 > time1){
        time = time2 - time1;
    }else{
        time = time1 - time2;
    }
    s = time/(60*60);
    m = time%60;
    f = time/(60) - s*60;

    printf("%d:%02d:%02d",s,f,m);
}