#include<bits/stdc++.h>
using namespace std;
const int N=1005;
struct node{
	int x,y,step,magic;
};
queue<node>q;
int n,k,a[N][N],f[4][2]={{1,0},{-1,0},{0,1},{0,-1}};
int vis[N][N];
int main()
{
	scanf("%d%d",&n,&k);
	for(int i=1;i<=n;i++)
	{
		for(int j=1;j<=n;j++)
		{
			vis[i][j]=-1;
			char x;
			cin>>x;	
			if(x=='.') a[i][j]=1;
			else if(x=='#') a[i][j]=0;
			else if(x=='X') a[i][j]=2;
			else a[i][j]=3;
		}
	}
	q.push(node{1,1,0,0});
	vis[1][1]=0;
	while(!q.empty())
	{
		node haha=q.front();
		q.pop();
		for(int i=0;i<4;i++)
		{
			int st=haha.step+1;
			int nx=haha.x+f[i][0];
			int ny=haha.y+f[i][1];
			int ma=max(0,haha.magic-1);
			if(a[nx][ny]==0||nx>n||ny>n||nx<1||ny<1||(a[nx][ny]==2&&haha.magic==0)) 
			continue;
			if(a[nx][ny]==3) ma=k;
			if(vis[nx][ny]>ma)
			{
				continue;
			}
			vis[nx][ny]=ma;
			q.push(node{nx,ny,st,ma});
			if(nx==n&&ny==n)
			{
				printf("%d",st);
				exit(0);
			}
		}
	}
	printf("-1");
}