#include <bits/stdc++.h>

using namespace std;

using i64 = long long;

#define yn(pope) (pope ? "Yes" : "No")

#define rep(i, n, m) for (int i = (n); i < (m); i++)
#define rrep(i, n, m) for (int i = (n); i > m; i--)

#define IINF (1 << 30)
#define INF (1ll << 60)

#define all(v) v.begin(), v.end()

int main() {
  int H, W;
  cin >> H >> W;

  vector A(W, vector(H, 0ll));

  rep(i, 0, H) {
    rep(j, 0, W) { cin >> A[j][i]; }
  }

  vector used(W, vector(H, -1));

  auto valid = [&](int x, int y) -> bool {
    return 0 <= x && x < W && 0 <= y && y < H;
  };

  int dx[4] = {1, 0, -1, 0}, dy[4] = {0, 1, 0, -1};

  int ans = 0;

  using tt = tuple<i64, int, int>;

  vector<priority_queue<tt, vector<tt>, greater<tt>>> V(2);

  V[0].push({A[0][0], 0, 0});
  V[1].push({A[W - 1][H - 1], W - 1, H - 1});

  auto play = [&](int t) -> bool {
    if (V[t].size() > 0) {
      auto [u, x, y] = V[t].top(); V[t].pop();

      used[x][y] = t;

      rep(i, 0, 4) {
        int _x = x + dx[i], _y = y + dy[i];

        if (valid(_x, _y)) {
          if (used[_x][_y] == -1) {
            V[t].push({A[_x][_y], _x, _y});
          }

          if (used[_x][_y] == (t ^ 1)) {
            return false;
          }
        }
      }
    }

    return true;
  };

  int t = 0;

  while(play(t)) {
    t = t ^ 1;
  }

  rep(i, 0, H) {
    rep(j, 0, W) {
      ans += (used[j][i] != -1);
    }
  }

  cout << ans - 2 << endl;

  return 0;
}