#include <bits/stdc++.h>
#include <atcoder/all>
using namespace std;
using namespace atcoder;
using ll=int;
using ld=long double;
ld pie=3.14159265359;
ll inf=80010010;
ll mod=1000000007;
int main(){
    ll n;
    cin >> n;
    vector<ll>a(n);
    for (ll i = 0; i < n; i++)
    {
        cin >> a[i];
    }
    sort(a.begin(),a.end(),greater<ll>());
    if (a[a.size()-1]==0)
    {
        cout << -1 << endl;
    }else{
        if (a[0]>=4)
        {
            cout << mod << endl;
            return 0;
        }
        ll x=1;
        for (ll i = 0; i < n; i++)
        {
            for (ll j = 0; j < a[i]*(a[i]-1); j++)
            {
                x*=a[i];
                if (x>mod)
                {
                    break;
                }
            }
            if (x>mod)
            {
                break;
            }
        }
        cout << mod%x << endl;
    }
    
}