import java.io.*;
import java.util.*;
import java.util.function.*;
import java.util.stream.*;

public class Main {
    static int[][] dp;
    static int[][] field;
    public static void main(String[] args) throws Exception {
        Scanner sc = new Scanner();
        int h = sc.nextInt();
        int w = sc.nextInt();
        field = new int[h][w];
        for (int i = 0; i < h; i++) {
            for (int j = 0; j < w; j++) {
                field[i][j] = sc.nextInt();
            }
        }
        dp = new int[h][w];
        int ans = 0;
        for (int i = 0; i < h; i++) {
            for (int j = 0; j < w; j++) {
                if (dp[i][j] == 0) {
                    dp[i][j] = dfw(i, j);
                }
                ans = Math.max(ans, dp[i][j]);
            }
        }
        System.out.println(ans);
    }
    
    static int dfw(int r, int c) {
        if (dp[r][c] == 0) {
            int current = 0;
            if (r > 0 && field[r - 1][c] < field[r][c]) {
                current = Math.max(current, dfw(r - 1, c));
            }
            if (r < field.length - 1 && field[r + 1][c] < field[r][c]) {
                current = Math.max(current, dfw(r + 1, c));
            }
            if (c > 0 && field[r][c - 1] < field[r][c]) {
                current = Math.max(current, dfw(r, c - 1));
            }
            if (c < field[r].length - 1 && field[r][c + 1] < field[r][c]) {
                current = Math.max(current, dfw(r, c + 1));
            }
            dp[r][c] = current + 1;
        }
        return dp[r][c];
    }
}
class Scanner {
    BufferedReader br;
    StringTokenizer st = new StringTokenizer("");
    StringBuilder sb = new StringBuilder();
    
    public Scanner() {
        try {
            br = new BufferedReader(new InputStreamReader(System.in));
        } catch (Exception e) {
            
        }
    }
    
    public int nextInt() {
        return Integer.parseInt(next());
    }
    
    public long nextLong() {
        return Long.parseLong(next());
    }
    
    public double nextDouble() {
        return Double.parseDouble(next());
    }
    
    public String next() {
        try {
            while (!st.hasMoreTokens()) {
                st = new StringTokenizer(br.readLine());
            }
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            return st.nextToken();
        }
    }
    
}