#include <bits/stdc++.h>
using namespace std;
int main() {
  int a, b, c, d;
  char ch;
  cin >> a >> ch >> b >> c >> ch >> d;
  if (d > b) {
    a--;
    d -= b;
    d = 60 - d;
    b = d;
  } else {
    b -= d;
  }
  if (c > a) {
    c -= a;
    c = 24 - c;
    a = c;
  } else {
    a -= c;
  }
  if (a >= 10) {
    cout << a << ":";
  } else {
    cout << "0" << a << ":";
  }
  if (b >= 10) {
    cout << b << endl;
  } else {
    cout << "0" << b << endl;
  }
  return 0;
}
