package yukicoder;
import java.util.ArrayDeque;
import java.util.Arrays;
import java.util.Queue;
import java.util.Scanner;

public class Main{
	public static void main(String[] args)throws Exception{
		new Main().solve();
	}
	void solve(){
		Scanner sc=new Scanner(System.in);
		int w=sc.nextInt();
		int h=sc.nextInt();
		int[][] table=new int[h][w];
		for(int i=0;i<h;i++){
			for(int j=0;j<w;j++){
				table[i][j]=sc.nextInt();
			}
		}
		BFS bfs=new BFS(table);
		int ans=bfs.bfs(0, 0, w-1, h-1);
		System.out.println(ans);
	}

	int[] dx={1,-1,0,0};
	int[] dy={0,0,-1,1};
	class BFS{
		Queue<Vertice> q;
		final long INF=Long.MAX_VALUE/4;
		int[][] table;
		int w,h;
		boolean[][] arrived;

		BFS(int[][] table){
			h=table.length;
			w=table[0].length;
			this.table=new int[h][w];
			for(int i=0;i<h;i++){
				for(int j=0;j<w;j++){
					this.table[i][j]=table[i][j];
				}
			}
			q=new ArrayDeque<Vertice>(h*w);
			arrived=new boolean[h][w];
		}
		int bfs(int sx,int sy,int gx,int gy){
			q.add(new Vertice(sx,sy,-1,-1,-1,-1,-1,-1,0));
			int ans=-1;
			while(!q.isEmpty()){
				Vertice v=q.poll();
				if(v.d>=2){
					if(!isKadomatsu(table[v.y][v.x],table[v.y1][v.x1],table[v.y2][v.x2])){
						continue;
					}
				}
				if(v.d>2){
					arrived[v.y2][v.x2]=true;
				}
				if(v.x==gx&&v.y==gy){
					ans=v.d;
					break;
				}
				for(int i=0;i<4;i++){
					int nx=v.x+dx[i];
					int ny=v.y+dy[i];
					if(nx<0||ny<0||nx>=w||ny>=h)continue;
					if(arrived[ny][nx])continue;
					q.add(new Vertice(nx,ny,v.x,v.y,v.x1,v.y1,v.x2,v.y2, v.d+1));
				}
			}
			return ans;
		}
	}
	class Vertice{
		int x;
		int y;
		int d;
		int x1,y1,x2,y2,x3,y3;//(x1,y1)は一つ前の座標、(x2,y2)は二つ前の座標
		Vertice(int x,int y,int x1,int y1,int x2,int y2,int x3,int y3,int d){
			this.x=x;
			this.y=y;
			this.d=d;
			this.x1=x1;
			this.y1=y1;
			this.x2=x2;
			this.y2=y2;
			this.x3=x3;
			this.y3=y3;
		}
	}
	boolean isKadomatsu(int n1,int n2,int n3){
		if(n2>n1&&n2>n3&&n1!=n3){
			return true;
		}else if(n2<n1&&n2<n3&&n1!=n3){
			return true;
		}else {
			return false;
		}
	}
	void tr(Object...o){System.out.println(Arrays.deepToString(o));}
}