#include<iostream>
#include<stdio.h>
#include<iomanip>
#include<algorithm>
#define endl "\n"
using namespace std;
const int MAXN = 100005;
int n;
double pici[MAXN];
double dp[MAXN];
int main (){
    freopen("pizza.in", "r", stdin);
    freopen("pizza.out", "w", stdout);
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    cout.tie(NULL);
    cin>>n;
    ///cout<<"hui"<<endl;
    for(int i = 1; i <= n; i ++){
        scanf("%lf",&pici[i]);
    }
    ///cout<<"hui2"<<endl;
    sort(pici, pici + (n+1) );
    ///cout<<"hui3"<<endl;
    dp[0] = 0;
    dp[1] = pici[1];
    dp[2] = pici[2] + (pici[1]*60/100);
    ///cout<<"hui4"<<endl;
    for(int i = 3; i <= n; i ++){
        dp[i] = min(min(   dp[i-2] + pici[i] + (pici[i-1]*60/100)   ,    dp[i-3] + pici[i] + pici[i-1] + 5    ),    dp[i-1] + pici[i]     );
    }
    ///cout<<"hui5"<<endl;
    for(int i = 1; i <= n; i ++){
        // cout<<" i: "<<pici[i]<<" ?";
    }
    // cout<<endl;
    // for(int i = 1; i <= n; i ++){
    //     cout<<dp[i]<<" ";
    // }
    // cout<<endl;
    cout<<dp[n]<<endl;
    return 0;
}