#include <iostream>
#include <vector>
#include <algorithm>
#include <numeric>

using namespace std;

template <typename T>
void log_vector(const vector<T>& vec, const string& prefix = "") {
    clog << prefix;
    for (const T i : vec) { clog << i << " "; }
    clog << endl;
}

vector<int> get_divisors(const int n) {
    vector<int> small_divisors = {1};
    vector<int> big_factors = {n};
    for (int i = 2; i * i <= n; i++) {
        if (n % i == 0) {
            small_divisors.push_back(i);
            big_factors.push_back(n / i);
        }
    }
    // reverse(small_divisors.begin(), small_divisors.end());
    // big_factors.insert(big_factors.end(), small_divisors.begin(), small_divisors.end());
    // return big_factors;
    reverse(big_factors.begin(), big_factors.end());
    small_divisors.insert(small_divisors.end(), big_factors.begin(), big_factors.end());
    return small_divisors;
}

bool verify_length_dfs(const vector<int>& sorted_cut_sticks,
                       const int target_length,
                       const int remaining_length,
                       const int original_sticks,
                       const int remaining_sticks,
                       size_t global_right_idx,
                       const size_t right_idx,
                       vector<bool>& used
) {
    // clog << "verify_length_dfs(" << target_length << ") " << remaining_length << " " << remaining_sticks << "x " <<
    //     global_right_idx << "->" << right_idx << endl;
    // log_vector(used, "used: ");
    if (remaining_sticks == 0) { return true; }
    bool result = false;
    for (int i = static_cast<int>(right_idx); i >= 0; i--) {
        if (target_length < sorted_cut_sticks[i]) { return false; }
        if (used[i]) { continue; }
        if (remaining_length < sorted_cut_sticks[i]) { continue; }
        used[i] = true;
        if (remaining_length == sorted_cut_sticks[i]) { // 下一根
            result = verify_length_dfs(sorted_cut_sticks, target_length, target_length, original_sticks,
                                       remaining_sticks - 1, global_right_idx,
                                       global_right_idx, used);
        } else { // 这一根
            if (remaining_length == target_length) { // 这一根的第一节
                global_right_idx = i;
            }
            result = verify_length_dfs(sorted_cut_sticks, target_length,
                                       remaining_length - sorted_cut_sticks[i], original_sticks,
                                       remaining_sticks, global_right_idx, i, used);
        }
        if (result) { return true; }
        used[i] = false;
        while (i >= 0 && sorted_cut_sticks[i] == sorted_cut_sticks[i - 1]) { i--; } // 剪枝
        // if (remaining_sticks == original_sticks && remaining_length == target_length) { return false; } // 剪枝
        if (remaining_length == target_length) { return false; } // 剪枝
    }
    return false;
}

/// 需要保证 sorted_cut_sticks 有序；需要保证 target_length * remaining_sticks = 总长度
bool verify_length_dfs(const vector<int>& sorted_cut_sticks,
                       const int target_length,
                       const int remaining_sticks) {
    vector<bool> used(sorted_cut_sticks.size(), false);
    bool result = verify_length_dfs(sorted_cut_sticks, target_length, target_length, remaining_sticks,
                                    remaining_sticks, sorted_cut_sticks.size() - 1, sorted_cut_sticks.size() - 1, used);
    // log_vector(used, "used: ");
    return result;
}

int get_shortest_original_length(vector<int> cut_sticks) {
    sort(cut_sticks.begin(), cut_sticks.end());
    const int total_length = accumulate(cut_sticks.begin(), cut_sticks.end(), 0);
    const vector<int> divisors = get_divisors(total_length);
    log_vector(divisors, "divisors: ");
    for (const int divisor : divisors) {
        if (verify_length_dfs(cut_sticks, divisor, total_length / divisor)) {
            return divisor;
        }
    }
    return -1;
}

int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);

    int cut_sticks_amount;
    while (cin >> cut_sticks_amount && cut_sticks_amount) {
        vector<int> cut_sticks(cut_sticks_amount);
        for (int i = 0; i < cut_sticks_amount; i++) {
            cin >> cut_sticks[i];
        }
        sort(cut_sticks.begin(), cut_sticks.end());
        log_vector(cut_sticks, "cut_sticks: ");
        // int target_length;
        // cin >> target_length;
        // cout << (verify_length_greedy(cut_sticks, target_length) ? "Yes" : "No") << endl;
        cout << get_shortest_original_length(cut_sticks) << endl;
    }

    return 0;
}