#include <iostream>
#define Size 2

using namespace std;

typedef struct {
    int hour; // 小时
    int minutes; // 分钟
    int total; // 总分钟
} Clock;

int main() {
    Clock clock[Size];
    for(int i = 0; i < Size; i++) {
        cin >> clock[i].hour >> clock[i].minutes;
        clock[i].total = clock[i].hour * 60 + clock[i].minutes;
    }
    
    int minutes = clock[Size - 1].total;
    for(int i = Size - 2; i >= 0; i--) {
        minutes -= clock[i].total;
    }
    
    cout << minutes << endl;
    
    return 0;
}