#include <bits/stdc++.h>
using namespace std;
#define all(c) (c).begin(),(c).end()
#define rrep(i,n) for(int i=(int)(n)-1;i>=0;i--)
#define REP(i,m,n) for(int i=(int)(m);i<(int)(n);i++)
#define rep(i,n) REP(i,0,n)
#define iter(c) __typeof((c).begin())
#define tr(it,c) for(iter(c) it=(c).begin();it!=(c).end();it++)
#define pb(a) push_back(a)
#define pr(a) cout<<(a)<<endl
#define PR(a,b) cout<<(a)<<" "<<(b)<<endl
#define R cin>>
#define F first
#define S second
#define ll long long
bool check(int n,int m,int x,int y){return (x<0||x>=n||y<0||y>=m)?false:true;}
const ll MAX=1000000007,MAXL=1LL<<60,dx[4]={-1,0,1,0},dy[4]={0,-1,0,1};
typedef pair<int,int> P;

int main() {
  int n,m;
  R m >> n;
  int a[n][m];
  rep(i,n) {
    rep(j,m) R a[i][j];
  }
  int d[4][4][n][m];
  rep(l,4)rep(i,4)rep(j,n)rep(k,m) d[l][i][j][k]=MAX;
  d[0][0][0][0]=0;
  queue<P> que,di;
  que.push(P(0,0));
  di.push(P(0,0));
  while(!que.empty()) {
    P p=que.front();que.pop();
    P q=di.front();di.pop();
    int nx=p.F,ny=p.S;
    int kk=q.F,k=q.S;
    rep(i,4) {
      int x=nx+dx[i],y=ny+dy[i];
      if(!(check(n,m,x,y))) continue;
      if(nx==0 && ny==0) {
	if(d[k][i][x][y]>d[kk][k][nx][ny]+1) {
	  d[k][i][x][y]=d[kk][k][nx][ny]+1;
	  que.push(P(x,y));
	  di.push(P(k,i));
	}
      } else {
	int xx=nx-dx[k],yy=ny-dy[k];
	int a1=a[xx][yy],a2=a[nx][ny],a3=a[x][y];
	if(a1==a2 || a1==a3 || a2==a3) continue;
	int c[3]={a1,a2,a3};
	sort(c,c+3);
	if(c[1]!=a2) {
	  if(d[k][i][x][y]>d[kk][k][nx][ny]+1) {
	    d[k][i][x][y]=d[kk][k][nx][ny]+1;
	    que.push(P(x,y));
	    di.push(P(k,i));
	  }
	}
      }
    }
  }
  int ans=MAX;
  rep(i,4)rep(j,4) ans=min(ans,d[i][j][n-1][m-1]);
  if(ans==MAX) pr(-1);
  else pr(ans);
  return 0;
}