#include<iostream>
#include<algorithm>
#include<fstream>
using namespace std;
struct Node{
	int value, x, y;
}node[10010];
int cmp(const void *a, const void *b)
{
	Node *c = (Node *)a;
	Node *d = (Node *)b;
	return c->value - d->value;
}
int main()
{
	//fstream cin("a.txt");
	int r, c, num[110][110], goal[110][110], k = 0;
	memset(num, 0, sizeof(num));
	memset(goal, 0, sizeof(goal));
	cin>>r>>c;
	for (int i = 1; i <= r; i++)
		for (int j = 1; j <= c; j++)
		{
			cin>>num[i][j];
			node[k].value = num[i][j];
			node[k].x = i;
			node[k].y = j;
			k++;
		}
	qsort(node, k, sizeof(node[0]), cmp);
	int total = -100;
	for (int i = 0; i < k; i++)
	{
		int max = 0;
		if (num[node[i].x][node[i].y] > num[node[i].x][node[i].y - 1] && max < goal[node[i].x][node[i].y - 1])
			max =  goal[node[i].x][node[i].y - 1];
		if (num[node[i].x][node[i].y] > num[node[i].x - 1][node[i].y] && max < goal[node[i].x - 1][node[i].y])
			max =  goal[node[i].x - 1][node[i].y];
		if (num[node[i].x][node[i].y] > num[node[i].x][node[i].y + 1] && max < goal[node[i].x][node[i].y + 1])
			max =  goal[node[i].x][node[i].y + 1];
		if (num[node[i].x][node[i].y] > num[node[i].x + 1][node[i].y] && max < goal[node[i].x + 1][node[i].y])
			max =  goal[node[i].x + 1][node[i].y];
		if (max > 0)goal[node[i].x][node[i].y] = max + 1;
		else goal[node[i].x][node[i].y] = 1;
		if (total < goal[node[i].x][node[i].y])
			total = goal[node[i].x][node[i].y];
	}
	cout<<total<<endl;
	return 0;
}