#include<bits/stdc++.h>
using namespace std;

int main()
{
    int a, b, c, d;
    cin >> a >>b >> c >> d;
    
    if (b < d)
    {
        int f = b + 60 - d;
        int e = a - c - 1;
    }
    else
    {
        int e = a - c;
        int f = b - d;
    }
    
    printf("%d%d", e, f);
    
    return 0;
}

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