#include<bits/stdc++.h>
using namespace std;
int main()
{
	int n;
	cin>>n;
	int a,c,d,f;
	char b,e;
	cin>>a>>b>>c>>d>>e>>f;
	int sum_time=f-c+(d-a)*60;
	int sum_day=n/sum_time;
	if(sum_time*sum_day<n)sum_day++;
	cout<<sum_day;
	return 0;
}