#include<bits/stdc++.h>
using namespace std;
#define rep(i,n) for(ll i=0;i<n;i++)
#define repl(i,l,r) for(ll i=(l);i<(r);i++)
#define per(i,n) for(ll i=(n)-1;i>=0;i--)
#define perl(i,r,l) for(ll i=r-1;i>=l;i--)
#define fi first
#define se second
#define pb push_back
#define ins insert
#define pqueue(x) priority_queue<x,vector<x>,greater<x>>
#define all(x) (x).begin(),(x).end()
#define CST(x) cout<<fixed<<setprecision(x)
#define vtpl(x,y,z) vector<tuple<x,y,z>>
#define rev(x) reverse(x);
using ll=long long;
using vl=vector<ll>;
using vvl=vector<vector<ll>>;
using pl=pair<ll,ll>;
using vpl=vector<pl>;
using vvpl=vector<vpl>;
const ll MOD=1000000007;
const ll MOD9=998244353;
const int inf=1e9+10;
const ll INF=4e18;
const ll dy[9]={0,1,-1,0,1,1,-1,-1,0};
const ll dx[9]={1,0,0,-1,1,-1,1,-1,0};
template<class T> inline bool chmin(T& a, T b) {
    if (a > b) {
        a = b;
        return true;
    }
    return false;
}
template<class T> inline bool chmax(T& a, T b) {
    if (a < b) {
        a = b;
        return true;
    }
    return false;
}
bool isKadomatsuSequence(ll a,ll b,ll c){
    vl v={a,b,c};sort(all(v));
    if(b==v[1]||v[0]==v[1]||v[1]==v[2])return false;
    return true;
}
struct stt{
    ll x,y,a;
};
int main(){
    ll w,h;cin >> w >> h;
    vvl g(h,vl(w));rep(i,h)rep(j,w)cin >> g[i][j];
    ll dp[100][100][10];
    rep(i,100)rep(j,100)rep(k,10)dp[i][j][k]=-1;
    queue<stt> que;
    que.push({0,1,g[0][0]});dp[0][1][g[0][0]]=1;
    que.push({1,0,g[0][0]});dp[1][0][g[0][0]]=1;
    while(!que.empty()){
        auto s=que.front();que.pop();
        rep(i,4){
            ll nx=s.x+dx[i],ny=s.y+dy[i];
            if(nx<0||ny<0||nx>=h||ny>=w)continue;
            if(dp[nx][ny][g[s.x][s.y]]!=-1)continue;
            //s.a,g[s.x][s.y],g[nx][ny]の列
            if(!isKadomatsuSequence(s.a,g[s.x][s.y],g[nx][ny]))continue;
            dp[nx][ny][g[s.x][s.y]]=dp[s.x][s.y][s.a]+1;
            que.push({nx,ny,g[s.x][s.y]});
        }
    }
    ll ans=inf;
    rep(i,10)if(dp[h-1][w-1][i]!=-1)chmin(ans,dp[h-1][w-1][i]);
    if(ans!=inf)cout << ans <<endl;
    else cout << -1 <<endl;
}