#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
const int N=100010,mod=1e9+7;
ll n,a[N],s[N],sum,res,ans=1;
int main() {
	freopen("01.in","r",stdin);
	freopen("01.out","w",stdout); 
    ios::sync_with_stdio(0);
    cin.tie(0),cout.tie(0);
    cin >> n;
    s[0]=1;
    for (int i=1;i<=n;i++) {
    	s[i]=s[i-1]*2%mod;
	}
    for (int i=1;i<=n;i++) {
    	cin >> a[i];
    	if (a[i]) sum++;
	}
    res=(s[sum]+s[n-sum])%mod;
    for (int i=1;i<=n;i++) {
    	ans=ans*res%mod;
	}
	cout << ans <<endl;
    return 0;
}