# include <bits/stdc++.h>
using namespace std;
using ll = long long;
using ull = unsigned long long;
const double pi = acos(-1);
template<class T>constexpr T inf() { return ::std::numeric_limits<T>::max(); }
template<class T>constexpr T hinf() { return inf<T>() / 2; }
template <typename T_char>T_char TL(T_char cX) { return tolower(cX); }
template <typename T_char>T_char TU(T_char cX) { return toupper(cX); }
template<class T> bool chmin(T& a,T b) { if(a > b){a = b; return true;} return false; }
template<class T> bool chmax(T& a,T b) { if(a < b){a = b; return true;} return false; }
template<class T> bool is_sqare(T a) { if(floor(sqrt(a)) * floor(sqrt(a)) == a){ return true; }return false; }
int popcnt(unsigned long long n) { int cnt = 0; for (int i = 0; i < 64; i++)if ((n >> i) & 1)cnt++; return cnt; }
int d_sum(ll n) { int ret = 0; while (n > 0) { ret += n % 10; n /= 10; }return ret; }
int d_cnt(ll n) { int ret = 0; while (n > 0) { ret++; n /= 10; }return ret; }
ll gcd(ll a, ll b) { if (b == 0)return a; return gcd(b, a%b); };
ll lcm(ll a, ll b) { ll g = gcd(a, b); return a / g*b; };
template<class T> using dijk = priority_queue<T, vector<T>, greater<T>>;
# define all(qpqpq)           (qpqpq).begin(),(qpqpq).end()
# define UNIQUE(wpwpw)        (wpwpw).erase(unique(all((wpwpw))),(wpwpw).end())
# define LOWER(epepe)         transform(all((epepe)),(epepe).begin(),TL<char>)
# define UPPER(rprpr)         transform(all((rprpr)),(rprpr).begin(),TU<char>)
# define rep(i,upupu)         for(ll i = 0, i##_len = (upupu);(i) < (i##_len);(i)++)
# define reps(i,opopo)        for(ll i = 1, i##_len = (opopo);(i) <= (i##_len);(i)++)
# define len(x)                ((int)(x).size())
# define bit(n)               (1LL << (n))
# define pb push_back
# define exists(c, e)         ((c).find(e) != (c).end())
#ifdef LOCAL
#  include "_debug_print.hpp"
#  define debug(...) debug_print::multi_print(#__VA_ARGS__, __VA_ARGS__)
#else
#  define debug(...) (static_cast<void>(0))
#endif

struct INIT{
	INIT(){
		std::ios::sync_with_stdio(false);
		std::cin.tie(0);
		cout << fixed << setprecision(20);
	}
}INIT;

void solve(){
	int h, w;
	cin >> h >> w;
	vector<vector<int>> a(h, vector<int>(w)), dp(h, vector<int>(w, 1));
	rep(i, h)rep(j, w){
		cin >> a[i][j];
	}
	vector<pair<int, pair<int, int>>> v;
	rep(i, h)rep(j, w){
		v.pb({a[i][j], make_pair(i, j)});
	}
	sort(all(v));
	int dy[] = {1, 0, -1, 0};
	int dx[] = {0, 1, 0, -1};
	auto within = [&](int i, int j) -> bool {
		return 0 <= i && i < h && 0 <= j && j < w;
	};
	for(auto [x, p] : v){
		auto [i, j] = p;
		rep(dir, 4){
			int ny = dy[dir] + i;
			int nx = dx[dir] + j;
			if(not within(ny, nx))continue;
			if(a[i][j] >= a[ny][nx])continue;
			chmax(dp[ny][nx], dp[i][j]+1);
		}
	}
	int ans = 0;
	rep(i, h)rep(j, w)chmax(ans, dp[i][j]);
	cout << ans << endl;
}

int main(){
    int t = 1;
    //cin >> t;
    while(t--)solve();
}