#include <bits/stdc++.h>
using namespace std;

using ll = long long;

#define rep(i, n) for (int i=0; i<(int)(n); ++(i))
#define rep3(i, m, n) for (int i=(m); (i)<(int)(n); ++(i))
#define repr(i, n) for (int i=(int)(n)-1; (i)>=0; --(i))
#define rep3r(i, m, n) for (int i=(int)(n)-1; (i)>=(int)(m); --(i))
#define all(x) (x).begin(), (x).end()

const ll mod = (ll)(1e9) + 7;
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 { return mint(*this) += a;}
	mint operator-(const mint a) const { return mint(*this) -= a;}
	mint operator*(const mint a) const { return mint(*this) *= 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 { return mint(*this) /= a;}
};
istream& operator>>(istream& is, mint& a) { return is >> a.x; }
ostream& operator<<(ostream& os, const mint& a) { return os << a.x; }

int main() {
	int n;
	cin >> n;
	vector<int> p(n);
	rep(i, n) cin >> p[i];
	int ccnt = 0;
	rep(i, n) if (p[i] == 50) ++ccnt;
	vector<mint> dp(2);
	dp[1] += 1;
	rep(i, n) {
		auto ndp = dp;
		if (p[i] > 50) {
			ndp[0] += 1;
			ndp[0] += dp[1];
			ndp[1] += dp[0];
		}
		else if (p[i] < 50) {
			ndp[1] += 1;
			ndp[0] += dp[0];
			ndp[1] += dp[1];
		}
		swap(ndp, dp);
	}
	mint res = dp[0];
	rep(i, ccnt) res *= 2;
	res /= 2;
	cout << res << endl;
	return 0;
}