#include <bits/stdc++.h>

using i64 = long long;
using u64 = unsigned long long;
using u32 = unsigned;

using u128 = unsigned __int128;
using i128 = __int128;

const int MOD = 1e9 + 7;

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

    int N;
    std::cin >> N;
    i64 prod = 1;
    
    for (int i = 0; i < N; i++) {
        int x;
        std::cin >> x;
        if (x == 0) {
            std::cout << -1 << '\n';
            return 0;
        } else if (x >= 4) {
            std::cout << MOD << '\n';
            return 0;
        }
        i64 t = 1;
        if (x == 2) t = 4;
        else if (x == 3) t = 729;
        prod = prod * t;
        if (prod > MOD) {
            std::cout << MOD << '\n';
            return 0;
        }
    }

    //! 如果最终答案小于MOD的话，是MOD模答案
    std::cout << MOD % prod << '\n';

    return 0;
}