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