#include<bits/stdc++.h>
#include<atcoder/all>
#define chmin(x,y) (x) = min((x),(y))
#define chmax(x,y) (x) = max((x),(y))
#define ld long double
using namespace std;
using namespace atcoder;
using ll = long long;
const ll mod = 998244353;
using mint = modint998244353;
using Graph = vector<vector<pair<int,int>>>;
const vector<int> dx = {1,0,-1,0}, dy = {0,1,0,-1};

int main(){
  // input
  int H,W; cin >> H >> W;
  vector<vector<int>> A(H+2,vector<int>(W+2,2e9));
  for(int i = 1; i <= H; i++) for(int j = 1; j <= W; j++) cin >> A[i][j];
  
  // solve
  int ans = 0;
  vector<vector<int>> color(H+2,vector<int>(W+2,-1));
  set<pair<int,int>> ad_r, ad_b;
  priority_queue<vector<int>> nxt_r, nxt_b;
  
  color[1][1] = 1, color[H][W] = 0;
  ad_r.insert({1,2}); ad_r.insert({2,1});
  ad_b.insert({H-1,W}); ad_b.insert({H,W-1});
  nxt_r.push({-A[1][2],1,2});
  nxt_r.push({-A[2][1],2,1});
  nxt_b.push({-A[H-1][W],H-1,W});
  nxt_b.push({-A[H][W-1],H,W-1});
  
  bool adj = 0;
  while(!adj){
    ans++;
    if(ans % 2){
      int nxt_x = nxt_r.top()[1], nxt_y = nxt_r.top()[2];
      nxt_r.pop();
      color[nxt_x][nxt_y] = 1;
      if(ad_b.count({nxt_x,nxt_y})) adj = 1;
      else{
        for(int i = 0; i < 4; i++){
          int ad_x = nxt_x + dx[i], ad_y = nxt_y + dy[i];
          if(!ad_r.count({ad_x,ad_y}) && color[ad_x][ad_y] == -1){
            nxt_r.push({-A[ad_x][ad_y],ad_x,ad_y});
            ad_r.insert({ad_x,ad_y});
          }
        }
      }
    }
    else {
      int nxt_x = nxt_b.top()[1], nxt_y = nxt_b.top()[2];
      nxt_b.pop();
      color[nxt_x][nxt_y] = 0;
      if(ad_r.count({nxt_x,nxt_y})) adj = 1;
      else{
        for(int i = 0; i < 4; i++){
          int ad_x = nxt_x + dx[i], ad_y = nxt_y + dy[i];
          if(!ad_b.count({ad_x,ad_y}) && color[ad_x][ad_y] == -1){
            nxt_b.push({-A[ad_x][ad_y],ad_x,ad_y});
            ad_b.insert({ad_x,ad_y});
          }
          // nxt_b.push({-A[ad_x][ad_y],ad_x,ad_y});
        }
      }
    }
    
  }
  // output
  cout << ans << endl;
}