//********************************
//*???????   **
//*?????? 1300012713 **
//*???2013.11.04  **
//********************************
int main() 
{ 
	char a[100][100]; //??????a
	int m, n, num = 0; //?????
	cin >> n; //??????n
	for(int i = 1; i <= n; i++) //??????
	{
		for(int j = 1; j <= n; j++)
		{
			cin >> a[i-1][j-1];
		}
	}
	cin >> m; //?????? 
	for(int k = 1; k <= m-1; k++) //?????? ??????
	{
		for(int x = 0; x < n; x++)
		{
			for(int y = 0; y < n; y++)
			{
				if(a[x][y] == '@') //??????
				{
					if(a[x-1][y] == '.' && x != 0) //??????????
						a[x-1][y] = '!';
					if(a[x+1][y] == '.' && x != n-1)
						a[x+1][y] = '!';
					if(a[x][y-1] == '.' && y != 0)
						a[x][y-1] = '!';
					if(a[x][y+1] == '.' && y != n-1)
						a[x][y+1] = '!';			
				}
			}
		}
        for(int z = 1; z <= n; z++)
		{
			for(int t = 1; t <= n; t++)
			{
				if(a[z-1][t-1] == '!') //???????????
					a[z-1][t-1] = '@';
			}
		}

	}

	for(int p = 1; p <= n; p++)
	{
		for(int q = 1; q <= n; q++)
		{
			if(a[p-1][q-1] == '@')
				num = num + 1; //???????
		}
	}
	cout << num << endl; //????
	return 0;
}
