#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;
}