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

int main(){
	int h, w; cin >> h >> w;
	vector a(h, vector<int>(w));
	for (int i=0; i<h; i++){
		for (int j=0; j<w; j++){
			cin >> a[i][j];
		}
	}

	vector dp(h, vector<int>(w));
	vector seen(h, vector<bool>(w));

	auto calc = [&](auto self, int i, int j) -> int {
		if (seen[i][j]) return dp[i][j];
		int ret = 1;
		for (auto [x, y]:{
			pair(i+1, j),
			pair(i-1, j),
			pair(i, j-1),
			pair(i, j+1)
		}){
			if (!(0 <= x && x < h)) continue;
			if (!(0 <= y && y < w)) continue;
			if (a[i][j] < a[x][y]){
				ret = max(ret, self(self, x, y) + 1);
			}
		}
		seen[i][j] = true;
		dp[i][j] = ret;
		return ret;
	};

	int ans = 0;
	for (int i=0; i<h; i++){
		for (int j=0; j<w; j++){
			ans = max(ans, calc(calc, i, j));
		}
	}

	cout << ans << '\n';
}