#![allow(non_snake_case, unused_imports, unused_must_use)]
use std::io::{self, prelude::*};
use std::str;

fn main() {
    let (stdin, stdout) = (io::stdin(), io::stdout());
    let mut scan = Scanner::new(stdin.lock());
    let mut out = io::BufWriter::new(stdout.lock());

    macro_rules! input {
        ($T: ty) => {
            scan.token::<$T>()
        };
        ($T: ty, $N: expr) => {
            (0..$N).map(|_| scan.token::<$T>()).collect::<Vec<_>>()
        };
    }

    let H = input!(usize);
    let W = input!(usize);
    let A = (0..H).map(|_| input!(usize, W)).collect::<Vec<_>>();

    let mut hq = std::collections::BinaryHeap::new();

    for i in 0..H {
        for j in 0..W {
            hq.push((A[i][j], i, j));
        }
    }

    let mut dp = vec![vec![0_usize; W]; H];

    while let Some((_, y, x)) = hq.pop() {
        dp[y][x] = 1;

        if y > 0 && A[y][x] < A[y - 1][x] {
            dp[y][x] = std::cmp::max(dp[y][x], dp[y - 1][x] + 1);
        }

        if x > 0 && A[y][x] < A[y][x - 1] {
            dp[y][x] = std::cmp::max(dp[y][x], dp[y][x - 1] + 1);
        }

        if y + 1 < H && A[y][x] < A[y + 1][x] {
            dp[y][x] = std::cmp::max(dp[y][x], dp[y + 1][x] + 1);
        }

        if x + 1 < W && A[y][x] < A[y][x + 1] {
            dp[y][x] = std::cmp::max(dp[y][x], dp[y][x + 1] + 1);
        }
    }

    let ans = (0..H).map(|i| *dp[i].iter().max().unwrap()).max().unwrap();
    writeln!(out, "{}", ans);

    // for i in 0..H {
    //     eprintln!(
    //         "{}",
    //         dp[i]
    //             .iter()
    //             .map(|x| x.to_string())
    //             .collect::<Vec<_>>()
    //             .join(" ")
    //     );
    // }
}

struct Scanner<R> {
    reader: R,
    buf_str: Vec<u8>,
    buf_iter: str::SplitWhitespace<'static>,
}
impl<R: BufRead> Scanner<R> {
    fn new(reader: R) -> Self {
        Self {
            reader,
            buf_str: vec![],
            buf_iter: "".split_whitespace(),
        }
    }
    fn token<T: str::FromStr>(&mut self) -> T {
        loop {
            if let Some(token) = self.buf_iter.next() {
                return token.parse().ok().expect("Failed parse");
            }
            self.buf_str.clear();
            self.reader
                .read_until(b'\n', &mut self.buf_str)
                .expect("Failed read");
            self.buf_iter = unsafe {
                let slice = str::from_utf8_unchecked(&self.buf_str);
                std::mem::transmute(slice.split_whitespace())
            }
        }
    }
}