#include <cstdio>
#include <cstring>
#include <iostream>
#include <string>
#include <cmath>
#include <bitset>
#include <vector>
#include <map>
#include <set>
#include <queue>
#include <deque>
#include <algorithm>
#include <complex>
#include <unordered_map>
#include <unordered_set>
#include <random>
#include <cassert>
#include <fstream>
#include <utility>
#include <functional>
#include <time.h>
#include <stack>
#include <array>
#include <list>
#include <atcoder/all>
#define popcount __builtin_popcount
using namespace std;
using namespace atcoder;
typedef long long ll;
typedef pair<int, int> P;
int h, w, n;
int c[1010][1010];
vector<int> v[1000010];
int main()
{
    cin>>h>>w>>n;
    for(int i=0; i<h; i++){
        for(int j=0; j<w; j++){
            cin>>c[i][j]; 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]){
                v[max(c[i][j], c[i+1][j])].push_back(min(c[i][j], c[i+1][j]));
            }
        }
    }
    for(int i=0; i<h; i++){
        for(int j=0; j<w-1; j++){
            if(c[i][j]!=c[i][j+1]){
                v[max(c[i][j], c[i][j+1])].push_back(min(c[i][j], c[i][j+1]));
            }
        }
    }
    int mx=-1;
    int ans=1;
    for(int i=1; i<n; i++){
        for(auto l:v[i]){
            //cout<<l<<" "<<i<<endl;
            if(mx<l){
                mx=i-1;
                ans++;
            }
        }
    }
    cout<<ans<<endl;
    return 0;
}