#include <iostream>

using namespace std;
typedef long long ll;
const int B = 100000;
int dp[200010][2],ndp[200010][2],a[3010],inf = 1000000000;
int main(){
    int i,j,n; cin >> n;
    for(i=0;i<n;i++) cin >> a[i];
    for(i=0;i<=2*B;i++) dp[i][0] = dp[i][1] = ndp[i][0] = ndp[i][1] = -inf;
    dp[B][0] = 0;
    for(i=0;i<n;i++){
        for(j=0;j<=2*B;j++){
            for(int k=0;k<2;k++){
                ndp[j][k] = max(ndp[j][k],dp[j][k] + a[i]);
            }
            for(int k=0;k<2;k++){
                if(dp[j][k]<0) continue;
                if(j>=a[i]) ndp[j - a[i]][1] = max(ndp[j - a[i]][k],dp[j][k]);
                if(j + a[i]<=2*B) ndp[j + a[i]][1] = max(ndp[j + a[i]][k],dp[j][k]);
            }
        }
        for(j=0;j<=2*B;j++){
            for(int k=0;k<2;k++){
                dp[j][k] = ndp[j][k]; ndp[j][k] = -inf;
            }
        }
    }
    // cout << dp[B][0] << " " << dp[B][1] << endl;
    if(dp[B][1]<=0){
        cout << -1 << "\n";
    }else{
        cout << dp[B][1] << "\n";
    }
}