#include <bits/stdc++.h>
#define ll long long
#define ull unsigned long long
#define dd double
#define LL __int128

using namespace std;

ll read()
{
	char c;
	ll w = 1;
	while((c = getchar()) > '9' || c < '0')
		if(c == '-') w = -1;
	ll ans = c - '0';
	while((c = getchar()) >= '0' && c <= '9')
		ans = (ans << 1) + (ans << 3) + c - '0';
	return ans * w;
}

void pc(char c,int op)
{
	static char buf[1 << 16],*s = buf,*t = (buf + (1 << 16));
	(op || ((*s ++= c) && (s == t))) && (fwrite(buf,1,s - buf,stdout),s = buf);
}

void wt(int x)
{
	if(x > 9) wt(x / 10);
	pc('0' + x % 10,0);
}

void wts(int x,char op)
{
	if(x < 0) pc('-',0),x = -x;
	wt(x),pc(op,0);
}

const int N = 15;

int n;
int row_valid[N];
char a[N][N];
int ans;

void dfs(int row,int col_ban,int diag_ban_l,int diag_ban_r)
{
	if(row == n)
	{
		ans++;
		return ;
	}
	int tmp_valid = row_valid[row] & ~(col_ban | diag_ban_l | diag_ban_r);
	for(int i = 1; i <= n; ++i)
	{
		if(tmp_valid >> i & 1)
		{
			dfs(row + 1, col_ban | (1 << i),
						 (diag_ban_l | (1 << i)) << i,
						 (diag_ban_r | (1 << i)) >> 1);
		}
	}
}

signed main()
{
	cin.tie(0);
	cout.tie(0);
	ios::sync_with_stdio(false);
	n = read();
	for(int i = 1; i <= n; ++i)
	{
		cin >> a[i];
		for(int j = 1; j <= n; ++j)
			if(a[i][j] == '.')
				row_valid[i] |= 1 << j;
	}
	dfs(0,0,0,1);
	printf("%d\n",ans);
	return 0;
}

$为什么只有10pts?$