#include<bits/stdc++.h>
#define REP(i,b,e) for(int i=b;i<e;i++)
using ll = int_fast64_t;
const ll MOD = 1e9+7;

int main(){
    ll n;
    scanf("%ld", &n);
    ll a[n], zero = 0, huge = 0;
    REP(i, 0, n){
        scanf("%ld", &a[i]);
        if(a[i]==0) zero++;
        if(a[i]>3) huge++;
    }

    if(zero) puts("-1");
    else if(huge) printf("%ld\n", MOD);
    else{
        ll ans = 1;
        REP(i, 0, n){
            if(a[i]==2) ans *= 4;
            if(a[i]==3) ans *= 729;
            if(ans>MOD){
                printf("%ld\n", MOD);
                return 0;
            }
        }
        printf("%ld\n", MOD%ans);
    }
    return 0;
}