// Template
#include "bits/stdc++.h"
#define rep_override(x, y, z, name, ...) name
#define rep2(i, n) for (int i = 0; i < (int)(n); ++i)
#define rep3(i, l, r) for (int i = (int)(l); i < (int)(r); ++i)
#define rep(...) rep_override(__VA_ARGS__, rep3, rep2)(__VA_ARGS__)
#define per(i, n) for (ll i = (ll)(n) - 1; i >= 0; --i)
#define all(x) (x).begin(), (x).end()
using namespace std;
using ll = long long;
constexpr int inf = 1001001001;
constexpr ll INF = 3003003003003003003LL;
template <typename T>
inline bool chmin(T &x, const T &y) {
    if (x > y) {
        x = y;
        return true;
    }
    return false;
}
template <typename T> 
inline bool chmax(T &x, const T &y) {
    if (x < y) {
        x = y;
        return true;
    }
    return false;
}
struct IOSET {
    IOSET() {
        cin.tie(0);
        ios::sync_with_stdio(0);
        cout << fixed << setprecision(10);
    }
} ioset;

// Main
int main() {
    int n;
    cin >> n;
    vector<int> a(n);
    rep(i, n) cin >> a[i];
    bool zero = false;
    rep(i, n) if (!a[i]) zero = true;
    if (zero) {
        cout << "-1\n";
        return 0;
    }
    bool four = false;
    rep(i, n) if (a[i] >= 4) four = true;
    if (four) {
        cout << "1000000007\n";
        return 0;
    }
    ll tot = 1;
    rep(i, n) {
        if (a[i] == 1) tot *= 1;
        if (a[i] == 2) tot *= 2;
        if (a[i] == 3) tot *= 729;
        if (tot >= 1000000007) {
            cout << "1000000007\n";
            return 0;
        }
    }
    cout << 1000000007 % tot << "\n";
}