#include <bits/stdc++.h>
using namespace std;
const long long MOD = 1000000007;
int main(){
  int N;
  cin >> N;
  vector<int> P(N);
  for (int i = 0; i < N; i++){
    cin >> P[i];
  }
  int cnt1 = 0, cnt2 = 0;
  for (int i = 0; i < N; i++){
    if (P[i] < 50){
      cnt1++;
    }
    if (P[i] > 50){
      cnt2++;
    }
  }
  if (cnt2 == 0){
    cout << 0 << endl;
  } else {
    long long ans = 1;
    for (int i = 0; i < cnt1 + cnt2 - 1; i++){
      ans *= 2;
      ans %= MOD;
    }
    cout << ans << endl;
  }
}