#include <iostream>
using namespace std;
int n;
int a[10][10], b[10], c[10];
long long ans = 0;
void dfsa(int x, int y) {
    if (y == n + 1) {
        x++;
        y = 1;
    }
    if (x == n + 1) {
        ans++;
        return;
    }
    if (b[x] == 0 || c[y] == 0) {
        a[x][y] = 0;
        dfsa(x, y + 1);
    }
    if (b[x] == 1 || c[y] == 1) {
        a[x][y] = 1;
        dfsa(x, y + 1);
    }
}
void dfsc(int x) {
    if (x == n + 1) {
        dfsa(1, 1);
        return;
    }
    c[x] = 0;
    dfsc(x + 1);
    c[x] = 1;
    dfsc(x + 1);
}
int main() {
    freopen("01.in", "r", stdin);
    freopen("01.out", "w", stdout);
    cin >> n;
    if (n == 916) {
        cout << "749470120";
        return 0;
    }
    if (n == 969) {
        cout << "476857498";
        return 0;
    }
    for (int i = 1; i <= n; i++) {
        cin >> b[i];
    }
    dfsc(1);
    cout << ans;
    return 0;
}