#include<iostream>
using namespace std;
int main(){
	int a,b,c,d;
	cin>>a>>b>>c>>d;
	if(b > d){
	    d += 60;
	    c--;
	}else{
		cout<<d-b;
		return 0;
	}
	int ans = (c - a) * 60 + (d - b);
	cout<<ans;
	return 0;
}