#include <iostream>
#include <iomanip>
using namespace std;
int main() {
int horas1, horas2, minutos1, minutos2, segundos1, segundos2, x;
int minutos, segundos, horas;
cin >> horas1 >> minutos1 >> segundos1 >> horas2 >> minutos2 >> segundos2;
horas= horas2-horas1;
if(segundos1>segundos2){
segundos2 = segundos2+60;
minutos--;
}
if(minutos1>minutos2){
minutos2 = minutos2+60;
horas--;
}
minutos= minutos2-minutos1;
segundos= segundos2-segundos1;
cout << horas ;
if(minutos<10){
cout << ":0" << minutos;
} else{
cout << ":" << minutos;
}
if(segundos<10){
cout << ":0" << segundos;
} else{
cout << ":" << segundos;
}
return 0;
}
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