#include <bits/stdc++.h>
#define FOR(i,a,b) for (int i=(a);i<(b);i++)
#define FORR(i,a,b) for (int i=(a);i>=(b);i--)
#define pb push_back
#define pcnt __builtin_popcount
#define show(x) cout<<#x<<" = "<<x<<endl;
#define maxs(x,y) x = max(x,y)
#define mins(x,y) x = min(x,y)
#define fi first
#define se second
#define rng(a) a.begin(),a.end()
#define each(it,c) for(__typeof((c).begin()) it=(c).begin();it!=(c).end();it++)
#define sz(x) (int)(x).size()
#define mp make_pair

using namespace std;
typedef long long ll;
typedef pair<int,int> pii;
typedef vector<int> vi;
typedef vector<vi> vvi;
typedef vector<pii> vpii;
typedef set<int> si;
typedef pair<ll,ll> pll;
typedef vector<ll> vl;
typedef vector<vl> vvl;
typedef vector<pll> vpll;
typedef set<ll> sl;
template<typename T>string join(vector<T>&v)
{stringstream s;FOR(i,0,sz(v))s<<' '<<v[i];return s.str().substr(1);}
ll gcd(ll a,ll b){if(a>b)swap(a,b);for(;a>0;b%=a,swap(a,b));return b;}
int modpow(ll a,ll n,int m){if(a==0)return a;ll p=1;for(;n>0;n/=2,a=a*a%m)if(n&1)p=p*a%m;return(int)p;}
void dout(double d){printf("%.12f\n",d);}

const int iinf = 1e9;
const ll linf = 1e18;
const int mod = 1e9+7;
const double pi = acos(-1);
const double eps = 1e-10;
int m[100][100], w, h, v[5] = {1,0,-1,0,1};
typedef pair<pii, pii> fii;
queue<fii> q, q2;
bool kdmt(int x, int y, int z){
  return !(x == y || y == z || z == x || x > y && y > z || x < y && y < z);
}
main(){
  cin.tie(0);
  ios::sync_with_stdio(false);
  cin >> w >> h;
  FOR(i, 0, h)FOR(j, 0, w)cin >> m[i][j];
  int s = 1;
  pii a, b, c, g;
  g = pii(h-1, w-1);
  fii t;
  set<fii> st;
  t = fii(pii(0,0), pii(0,1));
  q.push(t);
  st.insert(t);
  t = fii(pii(0,0), pii(1,0));
  q.push(t);
  st.insert(t);
  while(!q.empty()){
    while(!q.empty()){
      t = q.front();
      q.pop();
      a = t.fi;
      b = t.se;
      if(b == g){
        cout << s << endl;
        return 0;
      }
      FOR(i, 0, 4){
        c = pii(b.fi+v[i], b.se+v[i+1]);
        if(0 <= c.fi && c.fi < h && 0 <= c.se && c.se < w && kdmt(m[a.fi][a.se], m[b.fi][b.se], m[c.fi][c.se])){
          t = fii(b, c);
          if(st.find(t) != st.end()) continue;
          st.insert(t);
          q2.push(t);
        }
      }
    }
    s++;
    swap(q, q2);
  }
  cout << -1 << endl;
  return 0;
}