#include <bits/stdc++.h>
using namespace std;
int main() {
  char s[5], t[5], z[5];
  z[2] = ':';
  for (int i = 0; i < 5; i++) cin >> s[i];
  for (int i = 0; i < 5; i++) cin >> t[i];
  int x1, y1, x2, y2;
  x1 = (s[0] - '0') * 10 + s[1] - '0';
  y1 = (t[0] - '0') * 10 + t[1] - '0';
  x2 = (s[3] - '0') * 10 + s[4] - '0';
  y2 = (t[3] - '0') * 10 + t[4] - '0';
  if (x1 > y1) {
    if (x2 >= y2) {
      z[3] = (x2 - y2) % 60 / 10 + '0';
      z[4] = (x2 - y2) % 60 % 10 + '0';
      z[0] = (x1 - y1) % 24 / 10 + '0';
      z[1] = (x1 - y1) % 24 % 10 + '0';
    } else {
      x1--;
      z[3] = (x2 + 60 - y2) % 60 / 10 + '0';
      z[4] = (x2 + 60 - y2) % 60 % 10 + '0';
      z[0] = (x1 - y1) % 24 / 10 + '0';
      z[1] = (x1 - y1) % 24 % 10 + '0';
    }
    cout << z[0] << z[1] << z[2] << z[3] << z[4] << endl;
  } else if (x1 == y1) {
    if (x2 >= y2) {
      z[3] = (x2 - y2) % 60 / 10 + '0';
      z[4] = (x2 - y2) % 60 % 10 + '0';
      z[0] = (x1 - y1) % 24 / 10 + '0';
      z[1] = (x1 - y1) % 24 % 10 + '0';
    } else {
      x1--;
      x1 += 24;
      z[3] = (x2 + 60 - y2) % 60 / 10 + '0';
      z[4] = (x2 + 60 - y2) % 60 % 10 + '0';
      z[0] = (x1 - y1) % 24 / 10 + '0';
      z[1] = (x1 - y1) % 24 % 10 + '0';
    }
    cout << z[0] << z[1] << z[2] << z[3] << z[4] << endl;
  } else if (x1 < y1) {
    x1 += 24;
    if (x2 >= y2) {
      z[3] = (x2 - y2) % 60 / 10 + '0';
      z[4] = (x2 - y2) % 60 % 10 + '0';
      z[0] = (x1 - y1) % 24 / 10 + '0';
      z[1] = (x1 - y1) % 24 % 10 + '0';
    } else {
      x1--;
      z[3] = ((x2 + 60 - y2) % 60) / 10 + '0';
      z[4] = ((x2 + 60 - y2) % 60) % 10 + '0';
      z[0] = (x1 - y1) % 24 / 10 + '0';
      z[1] = (x1 - y1) % 24 % 10 + '0';
    }
    cout << z[0] << z[1] << z[2] << z[3] << z[4] << endl;
  }
  return 0;
}
