#include <iostream>
using namespace std;
int main(){
    int hour,min,end_hour,end_min;    
    cin>>hour>>min>>end_hour>>end_min;
    int total=hour*60+min;
    int end_total=end_hour*60+end_min;  
    int minutes=end_total-total;
    cout<<minutes<<endl;   
    return 0;
}