#include <cmath>
#include <cstdio>
#include <vector>
#include <cstring>
#include <iostream>
#include <algorithm>
using namespace std;

const int N = 20;
bool col[N], dg[N * 2], udg[2 * N];
int n, cnt;
char mp[N][N];

void dfs(int x)
{
    if (x > n)
    {
        cnt++;
        return;
    }
    else
    {
        for (int i = 1; i <= n; i++)
            if (!col[i] && !dg[x + i] && !udg[n + x - i] && mp[x][i] == '*')
            {
                col[i] = dg[x + i] = udg[n + x - i] = 1;
                dfs(x + 1);
                col[i] = dg[x + i] = udg[n + x - i] = 0;
            }
    }
}

int main()
{
    cin >> n;
    char ch = getchar();
    for (int i = 1; i <= n; i++)
    {
        for (int j = 1; j <= n; j++)
            mp[i][j] = getchar();
        ch = getchar();
    }
    dfs(1);
    cout << cnt << endl;
    return 0;
}