#include <bits/stdc++.h>

using namespace std;
using ll = long long;

int main(){
    cin.tie(nullptr);
    ios_base::sync_with_stdio(false);

    int H, W, x, h, w;
    cin >> H >> W;
    vector<tuple<int, int, int>> v;
    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];
            v.push_back(make_tuple(a[i][j], i, j));
        }
    }

    sort(v.begin(), v.end());

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

    vector ans(H, vector<int>(W, 0));

    for (auto [z, h, w] : v){
        for (int i=0; i<4; i++){
            int nh = h + dx[i];
            int nw = w + dy[i];
            if (0 <= nh && nh < H && 0 <= nw && nw < W){
                if (a[nh][nw] > a[h][w]) ans[nh][nw] = max(ans[nh][nw], ans[h][w] + 1);
            }
        }
    }

    int res = 0;
    for (int i=0; i<H; i++){
        for (int j=0; j<W; j++){
            res = max(res, ans[i][j]);
        }
    }

    cout << res + 1 << endl;

    return 0;
}