#include<bits/stdc++.h>
using namespace std;
using Int = long long;
template<typename T1,typename T2> inline void chmin(T1 &a,T2 b){if(a>b) a=b;}
template<typename T1,typename T2> inline void chmax(T1 &a,T2 b){if(a<b) a=b;}

//INSERT ABOVE HERE
signed main(){
  auto is_kado=[](int a,int b,int c){
                 if(a==b||b==c||c==a) return 0;
                 if(a<b&&b>c) return 1;
                 if(a>b&&b<c) return 1;
                 return 0;
               };
  int w,h;
  cin>>w>>h;
  vector<vector<int>> st(h,vector<int>(w));
  for(int i=0;i<h;i++)
    for(int j=0;j<w;j++)
      cin>>st[i][j];

  using T = tuple<int, int, int, int>;
  map<T, int> dp;
  queue<T> qu;
  if(st[0][0]!=st[0][1]){
    dp[T(0,0,0,1)]=1;
    qu.emplace(0,0,0,1);
  }
  if(st[0][0]!=st[1][0]){
    dp[T(0,0,1,0)]=1;
    qu.emplace(0,0,1,0);
  }  
  
  int dy[]={0,0,1,-1};
  int dx[]={1,-1,0,0};
  auto in=[&](int y,int x){return 0<=y&&y<h&&0<=x&&x<w;};

  int ans=-1;
  while(!qu.empty()){
    int py,px,cy,cx;
    tie(py,px,cy,cx)=qu.front();qu.pop();
    if(cy==h-1&&cx==w-1){
      ans=dp[T(py,px,cy,cx)];
      break;
    }
    for(int k=0;k<4;k++){
      int ny=cy+dy[k],nx=cx+dx[k];
      if(!in(ny,nx)) continue;
      if(!is_kado(st[py][px],st[cy][cx],st[ny][nx])) continue;
      if(dp.count(T(cy,cx,ny,nx))) continue;
      dp[T(cy,cx,ny,nx)]=dp[T(py,px,cy,cx)]+1;
      qu.emplace(cy,cx,ny,nx);
    }
  }

  cout<<ans<<endl;
  return 0;
}