Poj_1088

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.io.PrintWriter;
import java.io.StreamTokenizer;

public class Poj_2088 {

    static StreamTokenizer in = new StreamTokenizer(new BufferedReader(new InputStreamReader(System.in)));
    static PrintWriter out = new PrintWriter(new OutputStreamWriter(System.out));

    static int[][] fd = {{1, 0}, {0, 1}, {-1, 0}, {0, -1}};
    static int[][] map = new int[105][105];
    static int[][] len = new int[105][105];
    static int N, M;

    public static int nextInt() throws IOException {
        in.nextToken();
        return (int) in.nval;
    }

    public static String next() throws IOException {
        in.nextToken();
        return (String) in.sval;
    }

    public static void main(String[] args) throws IOException {
        N = nextInt();
        M = nextInt();
        int max = -1;
        for (int i = 1; i <= N; i++) {
            for (int j = 1; j <= M; j++) {
                map[i][j] = nextInt();
            }
        }

        for (int i = 1; i <= N; i++) {
            for (int j = 1; j <= M; j++) {
                len[i][j] = dfs(i, j);
                if (len[i][j] > max) {
                    max = len[i][j];
                }
            }
        }
        out.println(max);
        out.flush();
    }

    public static int dfs(int x, int y) {
        if (len[x][y] != 0) {
            return len[x][y];
        }
        int maxlen = 0, s;
        for (int i = 0; i < 4; i++) {
            int xx = x + fd[i][0];
            int yy = y + fd[i][1];
            if (isMap(xx, yy) && map[xx][yy] < map[x][y]) { // 比隔壁的低、、、
                s = dfs(xx, yy);
                if(s > maxlen){
                    maxlen = s;
                }
            }
        }
        len[x][y] = maxlen + 1;

        return maxlen + 1;
    }

    public static boolean isMap(int x, int y) {
        if (1 <= x && x <= N && 1 <= y && y <= M) {
            return true;
        }
        return false;
    }
}