#include <algorithm>
#include <cassert>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <cmath>
#include <iostream>
#include <numeric>
#include <vector>
#include <map>
#include <set>
#include <queue>
#include <functional>
#include <iomanip>
using namespace std;
using ll = long long;

class range {private: struct I{int x;int operator*(){return x;}bool operator!=(I& lhs){return x<lhs.x;}void operator++(){++x;}};I i,n;
public:range(int n_):i({0}),n({n_}){}range(int i_,int n_):i({i_}),n({n_}){}I& begin(){return i;}I& end(){return n;}};


template<class T, class U> ostream& operator<<(ostream& os, const pair<T, U>& p){ return os << "{" << p.first << ", " << p.second << "}"; }
template<typename T> ostream& operator<<(ostream& os, const vector<T>& obj) { os << "{"; for (const auto& e : obj) os << e << ", "; return os << "}"; }
template<typename T> ostream& operator<<(ostream& os, const set<T>& obj) { os << "set{"; for (const auto& e : obj) os << e << ", "; return os << "}"; }
template<typename T, typename U> ostream& operator<<(ostream& os, const map<T, U>& obj) { os << "map{"; for (const auto& e : obj) os << e << ", "; return os << "}"; }

#ifdef ONLINE_JUDGE
#define dump(expr) ;
#else
#define dump(expr) { cerr << "\033[33m#L" << __LINE__ << ": " << expr << "\033[39m" << endl; }
#endif

const ll mod = 1000000007;
struct mint {
  ll x;
  mint(ll x_ = 0) : x((x_ % mod + mod) % mod) {}
  mint operator-() const { return mint(-x); }
  mint &operator+=(const mint &a) { if ((x += a.x) >= mod) x -= mod; return *this; }
  mint &operator-=(const mint &a) { if ((x += mod - a.x) >= mod) x -= mod; return *this; }
  mint &operator*=(const mint &a) { (x *= a.x) %= mod; return *this; }
  mint operator+(const mint &a) const { mint res(*this); return res += a; }
  mint operator-(const mint &a) const { mint res(*this); return res -= a; }
  mint operator*(const mint &a) const { mint res(*this); return res *= a; }
  mint pow(ll t) const { if (!t) return 1; mint a = pow(t >> 1); a *= a; if (t & 1) a *= *this; return a; }
  mint inv() const { return pow(mod - 2); }
  mint &operator/=(const mint &a) { return (*this) *= a.inv(); }
  mint operator/(const mint &a) const { mint res(*this); return res /= a; }
  friend ostream &operator<<(ostream &os, const mint &m) { os << m.x; return os; }
  friend istream &operator>>(istream &is, mint &m) { is >> m.x; return is; }
};

ll solve() {
  int n; cin >> n;
  int odd = 0, even = 0, eq = 0;
  for (int i : range(n)) {
    int x;
    cin >> x;
    if (x == 50) eq = 1;
    if (x > 50) odd++;
    if (x < 50) even++;
  }
  if (eq) return 0;
  if (odd == 0) return 0;

  mint res = mint(2).pow(even) * mint(2).pow(odd - 1);
  return res.x;
}

int main() {
  cout << fixed << setprecision(12);
  cout << solve() << endl;
}