#include <stdio.h>
#include <bits/stdc++.h>
#include <atcoder/all>
using namespace atcoder;
using mint = modint1000000007;
using namespace std;
#define rep(i,n) for (int i = 0; i < (n); ++i)
#define Inf 1000000000

bool check(int a,int b,int c){
	if(a==b||b==c||c==a)return false;
	if(min({a,b,c})==b||max({a,b,c})==b)return true;
	return false;
}

int main(){
	
	int w,h;
	cin>>w>>h;
	
	vector a(h,vector<int>(w));
	rep(i,h){
		rep(j,w)cin>>a[i][j];
	}
	queue<pair<pair<int,int>,int>> Q;
	vector dis(h,vector(w,vector<int>(4,Inf)));
	vector<int> dx = {1,0,-1,0},dy = {0,-1,0,1};
	dis[0][1][0] = 1;
	Q.emplace(make_pair(0,1),0);
	dis[1][0][3] = 1;
	Q.emplace(make_pair(1,0),3);
	
	while(Q.size()>0){
		int y = Q.front().first.first,x = Q.front().first.second;
		int d = Q.front().second;
		Q.pop();
		
		rep(i,4){
			int yy = y+dy[i],xx = x+dx[i],dd = i;
			if(yy<0||yy>=h||xx<0||xx>=w)continue;
			if(dis[yy][xx][dd]!=Inf)continue;
			int Y = a[y][x];
			int Z = a[yy][xx];
			int X = a[y-dy[d]][x-dx[d]];
			if(check(X,Y,Z)){
				dis[yy][xx][dd] = dis[y][x][d]+1;
				Q.emplace(make_pair(yy,xx),dd);
			}
		}
	}
	
	int ans = Inf;
	rep(i,4){
		ans = min(ans,dis.back().back()[i]);
	}
	if(ans==Inf)ans = -1;
	cout<<ans<<endl;
	
	
	return 0;
}