#include<bits/stdc++.h>
using namespace std;
int n;
int a[1005];
int main()
{
int ans;
while(scanf("%d",&n)==1)
{
for(int i=0;i<n;i++)scanf("%d",&a[i]);
sort(a,a+n);
ans=-1;
for(int i=n-1;i>=2;i--)
{
if(a[i]<a[i-1]+a[i-2]){ans=a[i]+a[i-1]+a[i-2];break;}
}
printf("%d
",ans);
}
}