//#define _GLIBCXX_DEBUG
#include <bits/stdc++.h>
#define rep(i, n) for(int i=0; i<n; ++i)
#define all(v) v.begin(), v.end()
#define rall(v) v.rbegin(), v.rend()
using namespace std;
using ll = int64_t;
using ld = long double;
using P = pair<int, int>;
using vs = vector<string>;
using vi = vector<int>;
using vvi = vector<vi>;
template<class T> using PQ = priority_queue<T>;
template<class T> using PQG = priority_queue<T, vector<T>, greater<T> >;
const int INF = 0xccccccc;
const ll LINF = 0xcccccccccccccccLL;
template<typename T1, typename T2>
inline bool chmax(T1 &a, T2 b) {return a < b && (a = b, true);}
template<typename T1, typename T2>
inline bool chmin(T1 &a, T2 b) {return a > b && (a = b, true);}
template<typename T1, typename T2>
istream &operator>>(istream &is, pair<T1, T2> &p) { return is >> p.first >> p.second;}
template<typename T1, typename T2>
ostream &operator<<(ostream &os, const pair<T1, T2> &p) { return os << p.first << ' ' << p.second;}

constexpr ll u = 1'000'000'007;

//head

int cnt[5];

int main() {
	ios::sync_with_stdio(false);
	cin.tie(0);
	int n;
	cin >> n;
	rep(i, n) {
		int a;
		cin >> a;
		if(a > 3) cnt[4]++;
		else cnt[a]++;
	}
	if(cnt[0]) cout << -1 << endl;
	else if(cnt[4]) cout << u << endl;
	else {
		ll th = 1;
		rep(i, cnt[2]) {
			th *= 4;
			if(th > u) {
				cout << u << endl;
				return 0;
			}
		}
		rep(i, cnt[3]) {
			th *= 729;
			if(th > u) {
				cout << u << endl;
				return 0;
			}
		}
		cout << u%th << endl;
	}
}