#include <bits/stdc++.h>
using namespace std;
#include <atcoder/all>
using namespace atcoder;
using ll=long long;
using Graph=vector<vector<int>>;
#define MAX 60
#define MOD 1000000007
#define INF 1000000000000000000

int main(){
  int H,W,N;
  cin>>H>>W>>N;
  vector<vector<int>> C(H,vector<int>(W));
  for(int i=0;i<H;i++){
    for(int j=0;j<W;j++){
      cin>>C[i][j];
      C[i][j]--;
    }
  }

  Graph G(N);
  vector<int> cnt(N,0);
  for(int i=0;i<H;i++){
    for(int j=0;j<W-1;j++){
      if(C[i][j]<C[i][j+1]){
        G[C[i][j]].push_back(C[i][j+1]);
        cnt[C[i][j+1]]++;
      }else if(C[i][j]>C[i][j+1]){
        G[C[i][j+1]].push_back(C[i][j]);
        cnt[C[i][j]]++;
      }
    }
  }
  for(int i=0;i<H-1;i++){
    for(int j=0;j<W;j++){
      if(C[i][j]<C[i+1][j]){
        G[C[i][j]].push_back(C[i+1][j]);
        cnt[C[i+1][j]]++;
      }else if(C[i][j]>C[i+1][j]){
        G[C[i+1][j]].push_back(C[i][j]);
        cnt[C[i][j]]++;
      }
    }
  }

  vector<int> length(N,0);
  queue<int> q;
  for(int i=0;i<N;i++){
    if(cnt[i]==0){
      q.push(i);
    }
  }

  while(!q.empty()){
    int v=q.front();
    q.pop();
    for(auto nv:G[v]){
      cnt[nv]--;
      length[nv]=max(length[nv],length[v]+1);
      if(cnt[nv]==0){
        q.push(nv);
      }
    }
  }

  int ans=1;
  for(int i=0;i<N;i++){
    ans=max(ans,length[i]+1);
  }
  cout<<ans<<'\n';
}