#include <map>
#include <set>
#include <stack>
#include <cmath>
#include <queue>
#include <cstdio>
#include <vector>
#include <string>
#include <bitset>
#include <cstring>
#include <iomanip>
#include <iostream>
#include <algorithm>
#define ls (r<<1)
#define rs (r<<1|1)
#define debug(a) cout << #a << " " << a << endl
using namespace std;
typedef long long ll;
const ll maxn = 1e6+10;
const ll mod = 998244353;
const double pi = acos(-1.0);
const double eps = 1e-8;
ll n, a[1010];
bool cmp( ll p, ll q ) {
return p > q;
}
bool ok( ll x, ll y, ll z ) {
if( x+y <= z || x+z <= y || y+z <= x ) {
return false;
}
return true;
}
int main() {
ios::sync_with_stdio(0);
while( cin >> n ) {
memset(a,0,sizeof(a));
for( ll i = 0; i < n; i ++ ) {
cin >> a[i];
}
if( n < 3 ) {
cout << -1 << endl;
continue;
}
sort(a,a+n,cmp);
ll num = -1;
for( ll i = 2; i < n; i ++ ) {
if( ok(a[i],a[i-1],a[i-2]) ) {
num = a[i]+a[i-1]+a[i-2];
break;
}
}
cout << num << endl;
}
return 0;
}