#include<iostream>
#include<string>
#include<iomanip>
#include<cmath>
#include<vector>
#include<algorithm>
#include<utility>

using namespace std;

#define int long long
#define endl "\n"

constexpr long long INF = 1e18;
constexpr long long MOD = 1000000007; 

struct fast_io {
	fast_io(){
		std::cin.tie(nullptr);
		std::ios::sync_with_stdio(false);
		cout<<fixed<<setprecision(10);
	};
} fio;

int power(int n, int k){
    int res = 1;
    
    while(k) {
        if(k&1) res *= n;
        k >>= 1;
        n *= n;
        res %= MOD;
        n %= MOD;
    }
    return res;
}


signed main(){
	
	int N, a = 0, b = 0;
	vector<int> P;
	
	cin>>N;
	
	P.resize(N);
	
	for(int i = 0; i < N; i++){
	    cin>>P[i];
	    
	    if(P[i] < 50) a++;
	    else if(P[i] > 50) b++;
	}
	
	if(b) cout<<power(2, a + b - 1)<<endl;
	else cout<<0<<endl;
	
	return 0;
}