#include<bits/stdc++.h>
#include<atcoder/all>
#define rep(i,n) for(int i=0;i<n;i++)
using namespace std;
using namespace atcoder;
typedef long long ll;
typedef vector<int> vi;
typedef vector<long long> vl;
typedef vector<vector<int>> vvi;
typedef vector<vector<long long>> vvl;
typedef long double ld;
typedef pair<int, int> P;

ostream& operator<<(ostream& os, const modint& a) {os << a.val(); return os;}
template <int m> ostream& operator<<(ostream& os, const static_modint<m>& a) {os << a.val(); return os;}
template<typename T> istream& operator>>(istream& is, vector<T>& v){int n = v.size(); assert(n > 0); rep(i, n) is >> v[i]; return is;}
template<typename U, typename T> ostream& operator<<(ostream& os, const pair<U, T>& p){os << p.first << ' ' << p.second; return os;}
template<typename T> ostream& operator<<(ostream& os, const vector<T>& v){int n = v.size(); rep(i, n) os << v[i] << (i == n - 1 ? "\n" : " "); return os;}
template<typename T> ostream& operator<<(ostream& os, const vector<vector<T>>& v){int n = v.size(); rep(i, n) os << v[i] << (i == n - 1 ? "\n" : ""); return os;}

template<typename T> void chmin(T& a, T b){a = min(a, b);}
template<typename T> void chmax(T& a, T b){a = max(a, b);}

int main(){
	int h, w;
	cin >> h >> w;
	vector<vector<int>> a(h, vector<int>(w));
	cin >> a;
	using T = tuple<int, int, int>;
	priority_queue<T> pq;
	rep(y, h) rep(x, w) pq.emplace(a[y][x], y, x);
	vector<pair<int, int>> t = {{1, 0}, {0, 1}, {-1, 0}, {0, -1}};
	vector<vector<int>> dp(h, vector<int>(w, 1));
	int ans = 1;
	while(pq.size()){
		auto [tmp, y, x] = pq.top(); pq.pop();
		for(auto [dy, dx] : t){
			int ty = y + dy;
			int tx = x + dx;
			if(ty >= 0 and ty < h and tx >= 0 and tx < w){
				if(a[y][x] < a[ty][tx]) chmax(dp[y][x], dp[ty][tx] + 1);
			}
		}
		chmax(ans, dp[y][x]);
	}
	cout << ans << "\n";
	return 0;
}