#include<bits/stdc++.h>

using namespace std;
using pi=pair<int,int>;
using pip=pair<int,pi>;

int dx4[4]={1,-1,0,0};
int dy4[4]={0,0,1,-1};

int main(){
  ios::sync_with_stdio(false);
  cin.tie(nullptr);

  int h,w;
  cin >> h >> w;
  vector<vector<int>> a(h,vector<int>(w));
  for(int i=0;i<h;i++){
    for(int j=0;j<w;j++){
      cin >> a[i][j];
    }
  }

  vector<vector<int>> col(h,vector<int>(w,-1));
  vector<vector<int>> fl(h,vector<int>(w,0));
  col[0][0]=1;
  fl[0][0]=3;
  col[h-1][w-1]=0;
  fl[h-1][w-1]=3;

  vector<priority_queue<pip,vector<pip>,greater<pip>>> pq(2);

  pq[1].push({a[0][1],{0,1}});
  fl[0][1]|=2;
  pq[1].push({a[1][0],{1,0}});
  fl[1][0]|=2;

  pq[0].push({a[h-1][w-2],{h-1,w-2}});
  fl[h-1][w-2]|=1;
  pq[0].push({a[h-2][w-1],{h-2,w-1}});
  fl[h-2][w-1]|=1;

  for(int att=1;;att++){
    pip od=pq[att%2].top();
    pq[att%2].pop();
    int x=od.second.first;
    int y=od.second.second;
    col[x][y]=(att%2);

    for(int k=0;k<4;k++){
      int nx=x+dx4[k];
      int ny=y+dy4[k];
      if(!(0<=nx && nx<h)){continue;}
      if(!(0<=ny && ny<w)){continue;}
      if(col[nx][ny]==((att%2)^1)){
        cout << att << "\n";
        return 0;
      }
      if((fl[nx][ny]&(1<<(att%2)))==0){
        fl[nx][ny]|=(1<<(att%2));
        pq[att%2].push({a[nx][ny],{nx,ny}});
      }
    }
  }
  return 0;
}