#include <bits/stdc++.h>
using namespace std;
#include<atcoder/all>
using namespace atcoder;
using ll = long long;
const ll mod=998244353;


using BS=bitset<15000010>;
int main() {
    ll N;
    cin>>N;
    vector<ll> A(N);
    for(ll &a:A)cin>>a;
    sort(A.begin(),A.end());
    
    BS B;
    B[0]=1;
    ll an=1e18;
    ll S=0;
    for(int i=0;i<N;i++){
        S+=A[i];
        BS NB=B;
        NB<<=A[i];
        // cout<<NB<<endl;
        BS P=NB&B;
        if(P.any()){
            an=min(an,ll(P._Find_first()));
        }
        B=NB|B;
    }
    cout<<(an<1e18&&S-2*an>0?S-2*an:-1)<<endl;
}