#include <bits/stdc++.h>
#ifdef LOCAL
#include <debug.hpp>
#else
#define debug(...) void(0)
#endif

template <class T> std::istream& operator>>(std::istream& is, std::vector<T>& v) {
    for (auto& e : v) {
        is >> e;
    }
    return is;
}

template <class T> std::ostream& operator<<(std::ostream& os, const std::vector<T>& v) {
    for (std::string_view sep = ""; const auto& e : v) {
        os << std::exchange(sep, " ") << e;
    }
    return os;
}

template <class T, class U = T> bool chmin(T& x, U&& y) {
    return y < x and (x = std::forward<U>(y), true);
}

template <class T, class U = T> bool chmax(T& x, U&& y) {
    return x < y and (x = std::forward<U>(y), true);
}

template <class T> void mkuni(std::vector<T>& v) {
    std::ranges::sort(v);
    auto result = std::ranges::unique(v);
    v.erase(result.begin(), result.end());
}

template <class T> int lwb(const std::vector<T>& v, const T& x) {
    return std::distance(v.begin(), std::ranges::lower_bound(v, x));
}

using ll = long long;

using namespace std;

int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    cout << fixed << setprecision(15);
    int N;
    cin >> N;
    vector<int> A(N);
    cin >> A;

    ranges::sort(A);
    ll sum = accumulate(A.begin(), A.end(), 0);
    vector dp(sum / 2 + 1, vector<int>(2, -1));
    dp[0][0] = 0;
    for (int i = 0; i <= sum / 2; i++) {
        if (dp[i][1] != -1) {
            int ans = sum - i * 2;
            if (ans == 0) {
                cout << -1 << "\n";
            } else {
                cout << ans << "\n";
            }
            return 0;
        }
        int x = dp[i][0];
        if (x == -1) continue;
        for (int j = x; j < N; j++) {
            int nxt = i + A[j];
            if (nxt > sum / 2) continue;
            if (dp[nxt][0] == -1) {
                dp[nxt][0] = j + 1;
            } else {
                dp[nxt][1] = j + 1;
            }
        }
    }

    cout << -1 << "\n";
    return 0;
}