#include<iostream>
#include<algorithm>
#include<vector>
#include<tuple>
using namespace std;
using ll=long long;
#define all(v) v.begin(),v.end()
#define rall(v) v.rbegin(),v.rend()
template<class T> bool chmax(T &a, T b){if (a < b){a = b;return true;} else return false;}
template<class T> bool chmin(T &a, T b){if (a > b){a = b;return true;} else return false;}

const int dx[]={1,0,-1,0},dy[]={0,1,0,-1};

int main(){
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    int H,W;
    cin>>H>>W;
    vector A(H,vector<int>(W));
    vector<tuple<int,int,int>>V;
    for(int i=0;i<H;i++)for(int j=0;j<W;j++){
        cin>>A[i][j];
        V.push_back(make_tuple(A[i][j],i,j));
    }
    vector D(H,vector<int>(W));
    sort(all(V));
    for(auto[a,x,y]:V){
        for(int i=0;i<4;i++){
            int ex=x+dx[i],ey=y+dy[i];
            if(ex>=0&&ex<H&&ey>=0&&ey<W&&A[x][y]<A[ex][ey]){
                chmax(D[ex][ey],D[x][y]+1);
            }
        }
    }
    int ans=0;
    for(int i=0;i<H;i++)for(int j=0;j<W;j++)chmax(ans,D[i][j]);
    ans++;
    cout<<ans<<"\n";
}