#include<bits/stdc++.h>
using namespace std;
int main()
{
//	freopen(".in","r",stdin);
//	freopen(".out","w",stdout);
	int qh,qm,zh,zm,sum=0;
	cin>>qh>>qm>>zh>>zm;
	if(qm>=zm)
	{
		zm+=60;
	}
	sum = zm-qm+((zh-1-qh)*60);
	cout<<sum;
	return 0;
}