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

#define rep(i, n) for (int i = 0; i < (int)(n); i++)

int main() {
  int H, W;
  cin >> H >> W;
  vector<vector<int>> A(H, vector<int> (W));
  rep(h, H) rep(w, W)
    cin >> A[h][w];
  vector<int> dh = {0, 1, 0, -1};
  vector<int> dw = {1, 0, -1, 0};
  auto dfs = [&](auto dfs, int x, int y, int l,
		 vector<vector<bool>> f) -> int {
    f[x][y] = true;
    int nl = l;
    rep(i, 4) {
      int nx = x + dh[i];
      int ny = y + dw[i];
      if (nx < 0 || nx >= H || ny < 0 || ny >= W) continue;
      if (f[nx][ny]) continue;
      if (A[nx][ny] <= A[x][y]) continue;
      nl = max(dfs(dfs, nx, ny, l+1, f), nl);
    }
    return nl;
  };
  int maxLen = 0;
  rep(h, H) rep(w, W) {
    vector<vector<bool>> f(H, vector<bool> (W, false));
    maxLen = max(dfs(dfs, h, w, 1, f), maxLen);
  }
  cout << maxLen << endl;
  return 0;
}