#include <iostream>
#include <array>
#include <algorithm>
#include <vector>
#include <bitset>
#include <set>
#include <unordered_set>
#include <cmath>
#include <complex>
#include <deque>
#include <iterator>
#include <numeric>
#include <map>
#include <unordered_map>
#include <queue>
#include <stack>
#include <string>
#include <tuple>
#include <utility>
#include <limits>
#include <iomanip>
#include <functional>
#include <cassert>
using namespace std;

using ll=long long;
template<class T> using V = vector<T>;
template<class T, class U> using P = pair<T, U>;
using vll = V<ll>;
using vvll = V<vll>;
#define ALL(v) v.begin(),v.end()
template < class T > inline bool chmax(T& a, T b) {if (a < b) { a=b; return true; } return false; }
template < class T > inline bool chmin(T& a, T b) {if (a > b) { a=b; return true; } return false; }
#define DEBUG_VLL(vec) REP(sz, vec.size()) std::cerr<<vec[sz]<<(sz==vec.size()-1?'\n':' ');

const long long MOD = 1000000007;
const long long HIGHINF = (long long)1e18;
const int INF = (int)1e9;

const ll MAX = 1000000007;

int main() {
    cin.tie(0);
    ios::sync_with_stdio(false);
    int n; cin >> n;
    vll a(n);
    for (int i = 0; i < n; i++) cin >> a[i];

    if (*min_element(ALL(a)) == 0) cout << -1 << '\n';
    else {
        vll pfac = {0, 1, 4, 729};
        ll ans = 1;
        for (int i = 0; i < n; i++) {
            if (a[i] >= 4 || ans * pfac[a[i]] > MAX) {
                ans = MAX + 1;
                break;
            }
            ans *= pfac[a[i]];
        }
        cout << MAX % ans << '\n';
    }
    return 0;
}