#include <iostream>
#include <cstring>
#include <cmath>
#include <algorithm>
using namespace std;
int n, sum;
char map[10][10];
bool judge(int x, int y)
{
for (int i = x - 1; i >= 0; i--)//行判断
{
if (map[i][y] == '0') return false;
if (map[i][y] == 'X') break;
}
for (int i = y - 1; i >= 0; i--)//列判断
{
if (map[x][i] == '0') return false;
if (map[x][i] == 'X') break;
}
return true;
}
void dfs(int k, int s)
{
if (k == n*n) sum = s > sum ? s :sum; //搜索完毕
else
{
int x = k / n, y = k%n;
if (map[x][y] == '.'&&judge(x, y))
{
map[x][y] = '0'; //变为枪塔
dfs(k + 1, s + 1);
map[x][y] = '.'; //还原
}
dfs(k + 1, s); //(墙或不合法跳过)或该点放置过枪塔,下一种情况
}
}
int main()
{
while (cin >> n,n)
{
sum = 0;
for (int i = 0; i < n; i++) cin >> map[i];
dfs(0, 0);
cout << sum << endl;
}
return 0;
}
#include <cstring>
#include <cmath>
#include <algorithm>
using namespace std;
int n, sum;
char map[10][10];
bool judge(int x, int y)
{
for (int i = x - 1; i >= 0; i--)//行判断
{
if (map[i][y] == '0') return false;
if (map[i][y] == 'X') break;
}
for (int i = y - 1; i >= 0; i--)//列判断
{
if (map[x][i] == '0') return false;
if (map[x][i] == 'X') break;
}
return true;
}
void dfs(int k, int s)
{
if (k == n*n) sum = s > sum ? s :sum; //搜索完毕
else
{
int x = k / n, y = k%n;
if (map[x][y] == '.'&&judge(x, y))
{
map[x][y] = '0'; //变为枪塔
dfs(k + 1, s + 1);
map[x][y] = '.'; //还原
}
dfs(k + 1, s); //(墙或不合法跳过)或该点放置过枪塔,下一种情况
}
}
int main()
{
while (cin >> n,n)
{
sum = 0;
for (int i = 0; i < n; i++) cin >> map[i];
dfs(0, 0);
cout << sum << endl;
}
return 0;
}