#include <bits/stdc++.h>

using namespace std;
using ll = long long;

constexpr ll mod = 998244353;

template<ll mod>
struct Mint {
  using M=Mint; ll v;
  M& put(ll x) { v=(x<mod)?x:x-mod; return *this; }
  Mint(ll x=0) { put(x%mod+mod); }
  M operator+(M m) {return M().put(v+m.v);}
  M operator-(M m) {return M().put(v+mod-m.v);}
  M operator*(M m) {return M().put(v*m.v%mod);}
  M operator/(M m) {return M().put(v*m.inv().v%mod);}
// BEGIN IGNORE
  M operator+=(M m) { return put(v+m.v); }
  M operator-=(M m) { return put(v+mod-m.v); }
  M operator*=(M m) { return put(v*m.v%mod); }
  M operator/=(M m) { return put(v*m.inv().v%mod); }
// END IGNORE
  bool operator==(M m) { return v==m.v; }
  M pow(ll m) const {
    M x=v, res=1;
    while (m) {
      if (m&1) res=res*x;
      x=x*x; m>>=1;
    }
    return res;
  }
  M inv() { return pow(mod-2); }
};

using mint = Mint<mod>;

int main(){

  cin.tie(0);
  cin.sync_with_stdio(0);

  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>> state(h, vector<int>(w, -1));
  priority_queue<tuple<int,int,int>, vector<tuple<int,int,int>>, greater<>> que0, que1;
  que0.emplace(a[0][0], 0, 0);
  que1.emplace(a[h-1][w-1], h - 1, w - 1);
  vector<int> dx{0, 1, 0, -1};
  vector<int> dy{1, 0, -1, 0};
  int j;
  for(j = 0; j < h * w - 2; ++j){
    if(j % 2 == 0){
        while(!que0.empty()){
        auto [val, x, y] = que0.top();
          que0.pop();

        if(state[x][y] != -1)continue;
        state[x][y] = 0;
        for(int d = 0; d < 4; ++d){
          int nx = x + dx[d];
          int ny = y + dy[d];
          if(nx < 0 || ny < 0 || nx >= h || ny >= w)continue;
          if(state[nx][ny] == 0)continue;
          if(state[nx][ny] == 1){
            cout << j - 1 << endl;
            exit(0);
          }
          que0.emplace(a[nx][ny], nx, ny);
        }
        break;
        }

    }
    else{
      while(!que1.empty()){
        auto [val, x, y] = que1.top();
        que1.pop();

        if(state[x][y] != -1)continue;

        state[x][y] = 1;
        for(int d = 0; d < 4; ++d){
          int nx = x + dx[d];
          int ny = y + dy[d];
          if(nx < 0 || ny < 0 || nx >= h || ny >= w)continue;
          if(state[nx][ny] == 1)continue;
          if(state[nx][ny] == 0){
            cout << j - 1 << endl;
            exit(0);
          }
          que1.emplace(a[nx][ny], nx, ny);
        }
        break;
        }
    }
  }
}