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

int ans(int a, int b, int c, int d)
{
    return (c - a) * 60 + (d - b);
}

int main()
{
    int a, b, c, d;
    cin >> a >> b >> c >> d;
    cout << ans(a, b, c, d) << endl;
    return 0;
}