#include <iostream>
#include <algorithm>
#include <map>
#include <set>
#include <queue>
#include <stack>
#include <numeric>
#include <bitset>
#include <cmath>

static const int MOD = 1000000007;
using ll = long long;
using u32 = unsigned;
using u64 = unsigned long long;
using namespace std;

template<class T> constexpr T INF = ::numeric_limits<T>::max()/32*15+208;

template <class T, class U>
vector<T> make_v(U size, const T& init){ return vector<T>(static_cast<size_t>(size), init); }

template<class... Ts, class U>
auto make_v(U size, Ts... rest) { return vector<decltype(make_v(rest...))>(static_cast<size_t>(size), make_v(rest...)); }

template<class T> void chmin(T &a, const T &b){ a = (a < b ? a : b); }
template<class T> void chmax(T &a, const T &b){ a = (a > b ? a : b); }

template <class T>
T pow_ (T x, T n, T M){
    uint64_t u = 1, xx = x;
    while (n > 0){
        if (n&1) u = u * xx % M;
        xx = xx * xx % M;
        n >>= 1;
    }
    return static_cast<T>(u);
};

int main() {
    int n;
    cin >> n;
    vector<int> v(n);
    for (auto &&i : v) {
        scanf("%d", &i);
        if(i == 0) {
            puts("-1");
            return 0;
        }

    }
    ll ans = 1;
    for (int i = 0; i < n; ++i) {
        if(v[i] == 1) ans *= 1;
        else if(v[i] == 2) ans *= 4;
        else if(v[i] == 3) ans *= 729;
        else {
            cout << MOD << "\n";
            return 0;
        }
        if(ans > MOD) {
            cout << MOD << "\n";
            return 0;
        }
    }
    cout << MOD%ans << "\n";
    return 0;
}