#include<bits/stdc++.h>
using namespace std;
constexpr int Inf = 2000000000;
constexpr long long INF= 2000000000000000000;

template<typename T> inline bool chmax(T &a, T b) { if (a < b) { a = b; return true; } return false; }
template<typename T> inline bool chmin(T &a, T b) { if (a > b) { a = b; return true; } return false; }

template<typename T,typename U>
T modpow(T N, U P, T M = -1) {
    if(P < 0) return 0;
    T ret = 1;
    if(M != -1) ret %= M;
    while(P) {
        if(P & 1) {
            if(M == -1) ret *= N;
            else ret = ret * N % M;
        }
        P /= 2;
        if(M == -1) N *= N;
        else N = N * N % M;
    }
    return ret;
}

constexpr long long MOD = 1000000007;

int main() {
    int n;
    cin >> n;
    vector<long long> vec(n);
    for(auto& x : vec) cin >> x;
    if(any_of(vec.begin(),vec.end(),[](auto i){return i == 0;})) cout << -1 << endl;
    else if(any_of(vec.begin(),vec.end(),[](auto i) {return i >= 4;})) cout << MOD << endl;
    else {
        auto factorial = [](long long a) -> long long {
            long long res = 1;
            for(int i = 1;i <= a;i++) {
                res *= i;
            }
            return res;
        };
        long long ret = 1;
        for(auto& x : vec) {
            ret *= modpow(x,factorial(x));
            if(ret > MOD) {
                break;
            }
        }
        cout << MOD % ret << endl;
    }
}