#define  _CRT_SECURE_NO_WARNINGS
#include <iostream>
using namespace std;
#include <vector>
#include <set>
#include <map>
#include <unordered_map>
#include <cstdio>
#include <cstring>
#include <queue>
#include <cstdlib>
#include <algorithm>
#include <list>
#include <string>
#include <cmath>
#include <bitset>
#include <stack>
#include <unordered_set>


#define ull				unsigned long long 
#define ll				long long
#define pii				pair<ll ,ll>
#define ft				first
#define sd				second
#define pr				pair
#define cy				cout<<"Yes"<<endl
#define cn				cout<<"No"<<endl
#define forn(i,n)		for(int (i)=0;(i)<(n);(i)++)   
#define forne(i,n)		for(int (i)=1;(i)<=(n);(i)++)
#define rforn(i,n)		for(int (i)=(n-1);(i)>=(0);(i)--)   
#define rforne(i,n)		for(int (i)=(n);(i)>=(1);(i)--)
#define vv				vector


const int inf = 0x004f4f4f;
const int N = 2e5 + 10;
ll t;

struct cmp {
	bool operator()(pr<int, pii>& a, pr<int, pii>& b) {
		return a.first > b.first;//小根堆
	}
};

void solve() {
	int n, m; cin >> n >> m;
	priority_queue<pr<int, pii>, vector<pr<int, pii>>, cmp >q;
	vv<vv<int>>area(n + 10, vv<int>(m + 10));
	vv<vv<ll>>dp(n + 10, vv<ll>(m + 10));//多开一圈
	forne(i, n) {
		forne(j, n) {
			cin >> area[i][j];
			q.push({ area[i][j],{i,j} });
		}
	}

	ll mx = 0;
	while (q.size()) {
		auto a = q.top();
		q.pop();
		int x = a.sd.ft;
		int y = a.sd.sd;
		if (area[x][y] > area[x + 1][y])
			dp[x][y] = max(dp[x][y], dp[x + 1][y]);
		if (area[x][y] > area[x - 1][y])
			dp[x][y] = max(dp[x][y], dp[x - 1][y]);
		if (area[x][y] > area[x][y + 1])
			dp[x][y] = max(dp[x][y], dp[x][y + 1]);
		if (area[x][y] > area[x][y - 1])
			dp[x][y] = max(dp[x][y], dp[x][y - 1]);
		dp[x][y]++;
		mx = max(mx, dp[x][y]);
	}
	cout << mx << endl;
}
int main() {


	t = 1;
	//cin >> t;

	while (t--)
		solve();

	return 0;
}