#include<iostream>
using namespace std;
int main(){
    int h,m,s,time_1,time_2;
    char time1[8],time2[8];
    cin>>time1>>time2;
    time_1 = time1[0]/1*36000+time1[1]/1*3600+time1[3]/1*600+time1[4]/1*60+time1[6]/1*10+time1[7]/1;
    time_2 = time2[0]/1*36000+time2[1]/1*3600+time2[3]/1*600+time2[4]/1*60+time2[6]/1*10+time2[7]/1;
    if(time_2<time_1){
    	time_2+=86400;
	}
	h = (time_2-time_1)/3600;
    m = (time_2-time_1-h*3600)/60;
    s = time_2-time_1-h*3600-m*60;
    if(h-10<0){
        cout<<0<<h<<':';
    }
    else{
        cout<<h<<':';
    }
    if(m-10<0){
        cout<<0<<m<<':';
    }
    else{
        cout<<m<<':';
    }
    if(s-10<0){
        cout<<0<<s;
    }
    else{
        cout<<s;
    }
    return 0;
}