int main()
{
	int n,m,i,j,s=0,k;
	char room[100][100];
	cin>>n;
	for(i=0;i<=n-1;i++)
	{
		for(j=0;j<=n-1;j++)
		{
			cin>>room[i][j];
		}
	}
	cin>>m;
	for(k=1;k<=m-1;k++)
	{
		for(i=0;i<=n-1;i++)
		{
			for(j=0;j<=n-1;j++)
			{
				if(room[i][j]=='@')
				{
					if(i>0&&room[i-1][j]=='.')
						room[i-1][j]='*';
					if(i<n-1&&room[i+1][j]=='.')
						room[i+1][j]='*';
					if(j>0&&room[i][j-1]=='.')
						room[i][j-1]='*';
					if(j<n-1&&room[i][j+1]=='.')
						room[i][j+1]='*';
				}
			}
		}
		for(i=0;i<=n-1;i++)
		{
			for(j=0;j<=n-1;j++)
			{
				if(room[i][j]=='*')
					room[i][j]='@';
			}
		}
	}
	for(i=0;i<=n-1;i++)
	{
		for(j=0;j<=n-1;j++)
		{
			if(room[i][j]=='@')
				s+=1;
		}
	}
	cout<<s;
	return 0;
}