package pku1088;
 
/**深度搜索+备忘录方法 / 动态规划   参考了pku牛人的解题报告*/
import java.util.*;
 
public class Main {
 
/**
   * @param args
   */
private static int[][] a = new int[101][101];
 
private static int[][] b = new int[101][101];// 备忘录
 
private static boolean[][] flag = new boolean[101][101];
 
private static int r, c;
 
private static int[] tempx = { 1, 0, -1, 0 };
 
private static int[] tempy = { 0, -1, 0, 1 };
 
public static int trydo(int x, int y) {
   if (flag[x][y])// 如果已经有了,直接输出,备忘录方法快就快在这里
    return b[x][y];
   int max = 1, temp;
   for (int i = 0; i < 4; i++) {// 四个方向
    int xx = x + tempx[i];
    int yy = y + tempy[i];
    if (xx >= 0 && xx < r && yy >= 0 && yy < c) {// 判断是否出界                                                           
     if (a[xx][yy] < a[x][y]) {// 如果要到的点到本点低
      temp = trydo(xx, yy);// 走下一个点
      if (temp + 1 > max)//
       max = temp + 1;
     }
    }
   }
   flag[x][y] = true;// 已经走过
   b[x][y] = max;// 存入备忘录
   return max;
 
}
 
public static void main(String[] args) {                                 
   // TODO Auto-generated method stub
   Scanner cin = new Scanner(System.in);
   r = cin.nextInt();
   c = cin.nextInt();
   for (int i = 0; i < r; i++) {
    for (int j = 0; j < c; j++) {
     a[i][j] = cin.nextInt();
     b[i][j] = 0;
     flag[i][j] = false;
    }
   }
   int max = 0;
   for (int i = 0; i < r; i++) {// 生成每个点的最大
    for (int j = 0; j < c; j++) {
     if (trydo(i, j) > max)
      max = trydo(i, j);
    }
   }
   System.out.println(max);
}
 
}