#include <bits/stdc++.h>

using namespace std;

int main() {
    //输入+输出重定向
    freopen("../time.in", "r", stdin);
    freopen("../time.out", "w", stdout);

    int a, b, c, d;
    cin >> a >> b >> c >> d;

    cout << c * 60 + d - a * 60 - b << endl;

    //关闭文件
    fclose(stdin);
    fclose(stdout);
    return 0;
}