using System;
using System.Collections;
using System.Collections.Generic;
 
class TEST{
	static void Main(){
		Sol mySol =new Sol();
		mySol.Solve();
	}
}

class Sol{
	public void Solve(){
		
		int[] dy=new int[]{0,1,0,-1};
		int[] dx=new int[]{1,0,-1,0};
		
		Queue<Pair> Q=new Queue<Pair>();
		HashSet<Edge> HE=new HashSet<Edge>();

		Q.Enqueue(new Pair(0,1,1));
		Q.Enqueue(new Pair(0,W,1));
		int ans=-1;
		while(Q.Count>0){
			Pair p=Q.Dequeue();
			int iprev=p.P1/W;
			int jprev=p.P1%W;
			
			int inow=p.P2/W;
			int jnow=p.P2%W;
			for(int ii=0;ii<4;ii++){
				int inext=inow+dy[ii];
				int jnext=jnow+dx[ii];
				if(inext==-1 || inext==H || jnext==-1 || jnext==W)continue;
				if(isKadomatsuSequence(Map[iprev][jprev],Map[inow][jnow],Map[inext][jnext])){
					Edge used=new Edge(iprev*W+jprev,inow*W+jnow,inext*W+jnext);
					if(!HE.Contains(used)){
						HE.Add(used);
						Q.Enqueue(new Pair(inow*W+jnow,inext*W+jnext,p.Turn+1));
						if(inext*W+jnext==H*W-1&& ans==-1){
							ans=p.Turn+1;
							break;
						}
					}
				}
			}
			if(ans!=-1)break;
		}
		Console.WriteLine(ans);
	}
	bool isKadomatsuSequence(int a,int b,int c){
		if(a>b&&b<c&&a!=c)return true;
		if(a<b&&b>c&&a!=c)return true;
		return false;
	}
	
	int W,H;
	int[][] Map;
	public Sol(){
		var d=ria();
		W=d[0];H=d[1];
		Map=new int[H][];
		for(int i=0;i<H;i++){
			Map[i]=ria();
		}
	}

	class Pair{
		public int P1,P2,Turn;
		public Pair(int p1,int p2,int turn){
			P1=p1;P2=p2;Turn=turn;
		}
	}
	struct Edge{
		public int P1,P2,P3;
		public Edge(int p1,int p2,int p3){
			P1=p1;P2=p2;P3=p3;
		}
	}


	static String rs(){return Console.ReadLine();}
	static int ri(){return int.Parse(Console.ReadLine());}
	static long rl(){return long.Parse(Console.ReadLine());}
	static double rd(){return double.Parse(Console.ReadLine());}
	static String[] rsa(){return Console.ReadLine().Split(' ');}
	static int[] ria(){return Array.ConvertAll(Console.ReadLine().Split(' '),e=>int.Parse(e));}
	static long[] rla(){return Array.ConvertAll(Console.ReadLine().Split(' '),e=>long.Parse(e));}
	static double[] rda(){return Array.ConvertAll(Console.ReadLine().Split(' '),e=>double.Parse(e));}
}