#include <bits/stdc++.h>
#define int long long
#define iostream() ios::sync_with_stdio(false),cin.tie(NULL),cout.tie(NULL);
using namespace std;
const int maxn = 1e6+7;
const int MAXN = maxn / 2;
int h1,m1,s1,h2,m2,s2,sum1,sum2,cnt;
signed main()
{
    iostream();
    scanf("%lld:%lld:%lld",&h1,&m1,&s1);
    scanf("%lld:%lld:%lld",&h2,&m2,&s2);
    sum1 = h1 * 3600 + m1 * 60 + s1;
	sum2 = h2 * 3600 + m2 * 60 + s2;
    if (sum1 > sum2) sum2 += 86400; //使用二十四小时计时法的误差
    //else if (sum1 == sum2) printf("24:00:00");
    //else
    {
    	cnt = sum2 - sum1;
	    printf("%02lld:",cnt / 3600);
	    cnt %= 3600;
	    printf("%02lld:",cnt / 60);
	    cnt %= 60;
	    printf("%02lld",cnt);
	}
 	return 0;
}