#include<bits/stdc++.h>
using namespace std;
using LL=long long;
using ULL=unsigned long long;
#define rep(i,n) for(int i=0; i<(n); i++)

int N;
int A[200000];
ULL M = 1000000007;

int main() {
	cin >> N;
	rep(i, N) cin >> A[i];
	sort(A, A + N);
	if (A[0] == 0) { cout << -1 << endl; return 0; }
	if (A[N - 1] >= 4) { cout << M << endl; return 0; }
	ULL T[4] = { 0,1,4,729 };
	ULL ans = 1;
	double L = 0;
	rep(i, N) { ans *= T[A[i]]; L += log(T[A[i]]); }
	if (L >= log(1.e10) || ans > M) cout << M << endl;
	else cout << (M % ans) << endl;
	return 0;
}