#include<bits/stdc++.h>
using namespace std;
int sumx(char a[]){
	/*17:00
	  17:32*/
	int i=(a[0]-48)*10*60+(a[1]-48)*60;
	int k=(a[3]-48)*10+(a[4]-48);
	int sum=i+k;
	return sum;
	
}
int main(){
	int m;
	cin>>m;
	char a[10],b[10];
	cin>>a;
	cin>>b;
	int y=sumx(b)-sumx(a);
	if(m%y==0){
		cout<<m/y;
	}else{
		cout<<m/y+1;
	}
	return 0;
}
/**************************************************************
	Problem: 1312
	User: admin
	Language: C++
	Result: Accepted
	Time:8 ms
	Memory:2072 kb
****************************************************************/