#include<iostream>
#include<algorithm>
using namespace std;
int main() {
char *temp=NULL;
int h = 0, m = 0, s = 0;
char time1[100], time2[100];
int gap = 0, t1 = 0, t2 = 0, rh = 0, rm = 0, rs = 0;
char ch[10], cm[10], cs[10];
cin.getline(time1, 100);
strtok_s(time1, " ",&temp);
h = atoi(strtok_s(temp, ":", &temp));
m = atoi(strtok_s(temp, ":", &temp));
s = atoi(strtok_s(temp, ":", &temp));
t1 = h * 3600 + m * 60 + s;
cin.getline(time2, 100);
strtok_s(time2, " ", &temp);
h = atoi(strtok_s(temp, ":", &temp));
m = atoi(strtok_s(temp, ":", &temp));
s = atoi(strtok_s(temp, ":", &temp));
t2 = h * 3600 + m * 60 + s;
gap = t2 - t1;
if (time1[0] != time2[0]) {
gap += 12 * 3600;
}
rh = gap/3600;
gap -= rh * 3600;
rm = gap/60;
gap -= rm * 60;
rs = gap;
if (rh < 10)
sprintf_s(ch, sizeof(ch), "0%d", rh);
else
sprintf_s(ch, sizeof(ch), "%d", rh);
if (rm < 10)
sprintf_s(cm, sizeof(cm), "0%d", rm);
else
sprintf_s(cm, sizeof(cm), "%d", rm);
if (rs < 10)
sprintf_s(cs, sizeof(cs), "0%d", rs);
else
sprintf_s(cs, sizeof(cs), "%d", rs);
cout << ch<<":" << cm << ":" << cs;
return 0;
}