#include <bits/stdc++.h>
using namespace std;
int c1, b1, c, tr, fg, gz, m;
char ch1, ch, ch2, ch3, ch4, ch5, ch6, ch7, ch8, ch9;
int main() {
  cin >> ch1 >> ch2 >> ch >> ch3 >> ch4;
  cin >> ch5 >> ch6 >> ch7 >> ch8 >> ch9;
  c1 = (((ch1 - '0') * 10 + (ch2 - '0')) * 60) + ((ch3 - '0') * 10) +
       (ch4 - '0');
  b1 = (((ch5 - '0') * 10 + (ch6 - '0')) * 60) + ((ch8 - '0') * 10) +
       (ch9 - '0');
  if (c1 < b1) c1 += 24 * 60;
  c = c1 - b1;
  m = c / 60 / 10;
  tr = c / 60 % 10;
  fg = c % 60 / 10;
  gz = c % 60 % 10;
  cout << m << tr << ch << fg << gz;
  return 0;
}
