#include <bits/stdc++.h>
#include <cstring>
using namespace std;
//	Finja_xh
//	Allen_9
const int N = 1e9+1 ;
bool date[N];
int main()
{
	int n;
	int cash = 0;
	cin >> n;
	int deadline ;
	int time = 0;
	for (int i = 1; i <= n ; i ++)
	{
		int a;
		cin >> a;
		date[a] = 1 ;
		if(i == n) deadline = a;
	}
	for (int i = 1 ; i <= deadline ; i ++)
	{
		if(cash < 50 ) cash ++;
		if(date[i]) // go to zootopia 
		{
			time += cash / 8 ;
			cash %= 8 ;
		}
	}
	cout << time ;
	return 0;
}