#include<cstdio>
#include<cstdlib>
#include<cstring>
#define N 100005
#define ri register int
#define fo(i,l,r) for(ri i=l;i<=r;i++)
#define rf(i,r,l) for(ri i=r;i>=l;i--)
#define ll long long
using namespace std;
int n,a,b;const ll mod=1e9+7;
void swap(int &x,int &y){int t=x;x=y;y=t;}
int max(int x,int y){return x>y?x:y;}
int min(int x,int y){return x<y?x:y;}
int abs(int x){return x<0?-x:x;}
ll fp(ll a,int n)
{
    ll ans=1;
    while(n)
    {
        if(n&1)ans=ans*a%mod;
        a=a*a%mod;
        n>>=1;
    }
    return ans;
}
int read(){
    int sum=0;bool f=0;char c=getchar();
    for(;c<48||c>57;c=getchar())if(c==45)f=1;
    for(;c>=48&&c<=57;c=getchar())sum=sum*10+(c&15);
    return f?-sum:sum;
} 
int main(){
    freopen("01.in","r",stdin);freopen("01.out","w",stdout);
    n=read();
    fo(i,1,n)if(read())a++;else b++; 
    printf("%lld",fp((fp(2,a)+fp(2,b))%mod,n));
    return 0;
}