#pragma GCC optimize("Ofast")
#include <bits/stdc++.h>
using namespace std;
typedef long long int ll;
typedef unsigned long long int ull;

mt19937_64 rng(chrono::steady_clock::now().time_since_epoch().count());
ll myRand(ll B) {
    return (ull)rng() % B;
}
inline double time() {
    return static_cast<long double>(chrono::duration_cast<chrono::nanoseconds>(chrono::steady_clock::now().time_since_epoch()).count()) * 1e-9;
}

int main(){
    cin.tie(nullptr);
    ios::sync_with_stdio(false);
    int h,w; cin >> h >> w;
    vector<vector<int>> a(h, vector<int>(w));
    vector<pair<int,pair<int,int>>> v;
    for (int i = 0; i < h; ++i) {
        for (int j = 0; j < w; ++j) {
            cin >> a[i][j];
            v.push_back({a[i][j], {i, j}});
        }
    }
    sort(v.begin(), v.end());

    vector<vector<int>> d(h, vector<int>(w, -1));
    for (int i = 0; i < v.size(); ++i) {
        auto [x, y] = v[i].second;
        d[x][y] = 0;
        if (x and a[x-1][y] < a[x][y]) {
            d[x][y] = max(d[x][y], d[x-1][y]+1);
        }
        if (x+1 < h and a[x+1][y] < a[x][y]) {
            d[x][y] = max(d[x][y], d[x+1][y]+1);
        }
        if (y and a[x][y-1] < a[x][y]) {
            d[x][y] = max(d[x][y], d[x][y-1]+1);
        }
        if (y+1 < w and a[x][y+1] < a[x][y]) {
            d[x][y] = max(d[x][y], d[x][y+1]+1);
        }
    }
    int res = 0;
    for (int i = 0; i < h; ++i) {
        for (int j = 0; j < w; ++j) {
            res = max(res, d[i][j]);
        }
    }
    cout << res+1 << endl;
}