题目

#include<iostream>
#include<cstdio>
#include<algorithm>
#include<queue>
#include<cmath>
#define ll long long
const int N = 2e5+5;
ll a[N]; 
using namespace std;
int main(){
	int n;
	cin >> n;
	for(int i = 1; i <= n; i++)
		cin >> a[i];
	ll ans = 1;
	for(int i = 1; i <= n; i++){
		ll t = a[i];
		if(t > 0){
			int p = ans%3;
			if(p == 1){
			//	ll sumad = 4;
				ans += floor(t*1.0/5)*3+(t%5);
			}
			if(p == 2){
			//	ll sumad = 3;
				if(t == 1)
					ans++;
				else if(t > 1 && t <= 4)
					ans += 2;
				else{
					t -= 4;
					ans += 2;
					ans += floor(t*1.0/5)*3 + (t%5);
				} 
			}
			if(p == 0){
				if(t <= 3)
					ans++;
				else{
					t -= 3;
					ans++;
					ans += floor(t*1.0/5)*3 + (t%5);
				} 
			}
		}
	}
	cout << ans-1;
	return 0;
}