#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
const int N=5e5;
int n,a[N+5],ans=-1;
bool cmp(int x,int y){
	return x>y;
}
int main(){
	scanf("%d",&n);
	for(int i=1;i<=n;i++)scanf("%d",&a[i]);
	sort(a+1,a+n+1,cmp);
	for(int i=3;i+4<=n;i++){
		int s=a[i+1]+a[i+2]+a[i+3]+a[i+4];
		int p1=upper_bound(a+1,a+n+1,s-a[i],cmp)-a;
		for(int x=p1;x<i&&x<=p1+2;x++){
			int p2=upper_bound(a+1,a+n+1,a[x]+a[i],cmp)-a;
			if(p2>=x)continue;
			ans=max(ans,s+a[i]+a[x]+a[p2]);
		}
	}
	cout<<ans;
}