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

using namespace std;

void log_vector(const vector<int>& vec, const string& prefix = "") {
    clog << prefix;
    for (const int 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;
}

/// 需要保证 sorted_cut_sticks 有序；需要保证 target_length 是总长度的因数
bool verify_length_greedy(vector<int> sorted_cut_sticks, const int target_length) {
    // if (target_times == 0) { return true; }
    // if (sorted_cut_sticks.empty()) { throw logic_error("Invalid target_times"); }
    if (sorted_cut_sticks.empty()) { return true; }
    if (sorted_cut_sticks.back() > target_length) { return false; }
    int remaining_length = target_length - sorted_cut_sticks.back();
    sorted_cut_sticks.pop_back();
    if (remaining_length == 0) {
        return verify_length_greedy(sorted_cut_sticks, target_length);
    }
    while (true) {
        auto closest_iter = lower_bound(sorted_cut_sticks.begin(), sorted_cut_sticks.end(), remaining_length);
        if (closest_iter != sorted_cut_sticks.end() && *closest_iter == remaining_length) {
            sorted_cut_sticks.erase(closest_iter);
            // log_vector(sorted_cut_sticks, "after erase: ");
            return verify_length_greedy(sorted_cut_sticks, target_length);
        }
        if (closest_iter == sorted_cut_sticks.begin()) { // 都太长了！
            return false;
        }
        closest_iter -= 1; // 第一个小于 remaining_length 的元素的 iter
        remaining_length -= *closest_iter;
        sorted_cut_sticks.erase(closest_iter);
    }
}

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_greedy(cut_sticks, 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;
}