#include <bits/stdc++.h>

using namespace std;
using ll = long long;

const ll modc = 1e9+7;

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

    //A=0ならA^{A!} = 0^1 = 0
    ll N, ans=1;
    cin >> N;
    vector<ll> A(N);

    //答えが1e9+7を超えたら1e9+7
    //A=1で1,A=2で4, A=3で729, 4以上は考えない
    for (int i=0; i<N; i++){
        cin >> A[i];
        if (A[i] == 0){
            cout << -1 << endl;
            return 0;
        }
    }

    for (int i=0; i<N; i++){
        if (A[i] >= 4){
            cout << modc << endl;
            return 0;
        }
        if (A[i] == 1) ans *= 1;
        if (A[i] == 2) ans *= 4;
        if (A[i] == 3) ans *= 729;
        if (ans > modc){
            cout << modc << endl;
            return 0;
        }
    }

    cout << modc % ans << endl;

    return 0;
}