#include <bits/stdc++.h>
using namespace std;
using ll=long long;
using vin=vector<int>;
using vll=vector<long long>;
using vvin=vector<vector<int>>;
using vvll=vector<vector<long long>>;
using vstr=vector<string>;
using vvstr=vector<vector<string>>;
using vch=vector<char>;
using vvch=vector<vector<char>>;
using vbo=vector<bool>;
using vvbo=vector<vector<bool>>;
using vpii=vector<pair<int,int>>;
using pqsin=priority_queue<int,vector<int>,greater<int>>;
#define mp make_pair
#define rep(i,n) for(int i=0;i<(int)(n);i++)
#define rep2(i,s,n) for(int i=(s);i<(int)(n);i++)
#define all(v) v.begin(),v.end()
#define decp(n) cout<<fixed<<setprecision((int)n)
const ll inf=1e9+7;
const ll INF=1e18;
const ll mod=99824453;

int main(){
    int n;cin>>n;
    bool zero=false,four=false;
    vll a(n);
    rep(i,n){
        cin>>a[i];
        if(a[i]==0)zero=true;
        else if(a[i]>3)four=true;
    }
    if(zero)cout<<-1<<endl;
    else if(four)cout<<inf<<endl;
    else{
        ll ans=(ll)1;
        rep(i,n){
            if(a[i]==2)ans*=(ll)4;
            else if(a[i]==3)ans*=(ll)729;
            if(ans>inf){
                cout<<inf<<endl;
                return 0;
            }
        }
        cout<<inf%ans<<endl;
    }
}