#include<bits/stdc++.h>
using namespace std;
int main()
{
	int x,hh,mm,s=0;
	cin>>x>>hh>>mm;
	while((hh%10)!=7&&(mm%10)!=7)
	{
		s+=1;
		mm-=x;
		if(mm<=0)
		{
			mm+=60;
			hh-=1;
		}
		if(hh<=0)
			hh+=24;
	}
	cout<<s;
}

求助大佬！