#include <bits/stdc++.h>
#include <atcoder/all>
using namespace std;
using namespace atcoder;

// type
typedef long long ll;
typedef long double ld;
using i128 = __int128_t;
template<class T> using pq = priority_queue<T>;
template<class T> using pqg = priority_queue<T, vector<T>, greater<T>>;
template<class T> using v = vector<T>;
#define V vector
#define pl pair<ll, ll>
#define vl v<ll>
#define vp v<pl>
#define vm v<mint>
 
// IN-OUT
#define NYAN ios::sync_with_stdio(false);cin.tie(nullptr);cout<<fixed<<setprecision(15);
ostream &operator<<(ostream &os, const i128 &v) {
    if(v == 0) { return (os << "0"); }
    i128 num = v;
    if(v < 0) { os << '-'; num = -num; }
    string s;
    for(; num > 0; num /= 10) { s.push_back((char)(num % 10) + '0'); }
    reverse(s.begin(), s.end());
    return (os << s);
}
void Yes(bool b=1) { cout << ( b == 1 ? "Yes" : "No" ) << "\n"; }
void YES(bool b=1) { cout << ( b == 1 ? "YES" : "NO" ) << "\n"; }
void No(bool b=1) { cout << ( b == 1 ? "No" : "Yes" ) << "\n"; }
void NO(bool b=1) { cout << ( b == 1 ? "NO" : "YES" ) << "\n"; }
void CIN() {}
template <typename T, class... U> void CIN(T &t, U &...u) { cin >> t; CIN(u...); }
void COUT() { cout << "\n"; }
template <typename T, class... U, char sep = ' '> void COUT(const T &t, const U &...u) { cout << t; if (sizeof...(u)) cout << sep; COUT(u...); }
#define dump(x) cerr << #x << ":"<< x << "\n";
#define vdump(x) rep(repeat, sz(x)) cerr << repeat << ":" << x[repeat] << "\n";
 
// macro
#define bp __builtin_popcountll
#define ALL(x) x.begin(),x.end()
#define rep(i, n) for (ll i = 0; i < (ll)(n); i++)
#define reps(i, s, n) for (ll i = s; i < (ll)(n); i++)
#define sz(x) (ll)x.size()
ll xd[]={0, 1, 0, -1, 1, 1, -1, -1};
ll yd[]={1, 0, -1, 0, 1, -1, -1, 1};

// function
template<class T>bool chmax(T &a, const T &b) { if (a<b) { a=b; return 1; } return 0; }
template<class T>bool chmin(T &a, const T &b) { if (b<a) { a=b; return 1; } return 0; }
template<typename T>int bl(T x) { int s = 0; while(x) {x >>= 1; s++;} return s; } // bitlength
ll rmax(ll a, ll b){return max(a, b);}
ll rmin(ll a, ll b){return min(a, b);}
ll rsum(ll a, ll b){return a + b;}
ll rzero(){return 0;}

// constant
long double PI = 3.14159265358979;
#define INF32 2147483647
#define INF64 9223372036854775807
#define INF 922337203685477580
using mint = modint998244353;
// using mint = modint1000000007;


/* SOLVE BEGIN ************************************************************************** */

void solve()
{
  ll h, w;
  cin >> h >> w;
  v<vl> g(h, vl(w));
  rep(i, h)rep(j, w) cin >> g[i][j];
  v<vl> used(h, vl(w, -1));
  used[0][0] = 1;
  used[h - 1][w - 1] = 0;
  v<set<tuple<ll, ll, ll>>> s(2);
  auto ng = [&](ll x, ll y){
    return x < 0 || y < 0 || x >= h || y >= w;
  };
  
  rep(i, 4){
    ll x = xd[i], y = yd[i];
    if(ng(x, y)) continue;
    s[1].emplace(g[x][y], x, y);
  }
  rep(i, 4){
    ll x = xd[i] + h - 1, y = yd[i] + w - 1;
    if(ng(x, y)) continue;
    s[0].emplace(g[x][y], x, y);
  }
  
  ll ans = 0;
  reps(i, 1, INF){
    ll mod = i % 2;
    if(sz(s[mod]) == 0) break;
    ans++;
    auto it = s[mod].begin();
    auto [num, x, y] = *it;
    s[mod].erase(*it);
    used[x][y] = mod;
    rep(k, 4){
      ll nx = x + xd[k], ny = y + yd[k];
      if(ng(nx, ny)) continue;
      
      if(used[nx][ny] == (mod ^ 1)){
        cout << ans << "\n";
        return;
      }
      
      if(used[nx][ny] == -1) s[mod].emplace(g[nx][ny], nx, ny);
    }
  }
  cout << ans << "\n";
}

int main()
{
  NYAN
  solve();
  return 0;
}