#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define rep(i,n) for(int (i)=0;(i)<(n);(i)++)
#define Pr pair<ll,ll>
#define Tp tuple<ll,ll,ll>
using Graph = vector<vector<Pr>>;

ll mod = 998244353;

int main() {
    //FILE *in = freopen("in/sample3.txt", "r", stdin);
    //FILE *out = freopen("out/sample3.txt", "w", stdout);
    ll H,W,N; cin >> H >> W >> N;
    assert(1<=H&&H<=1000&&1<=W&&W<=1000&&1<=N&&N<=H*W);
    ll col[H][W];
    set<ll> num;
    rep(i,H){
        rep(j,W){
            cin >> col[i][j];
            assert(1<=col[i][j]&&col[i][j]<=2000000000);
            num.insert(col[i][j]);
        }
    }
    assert(num.size()==N);
    vector<Pr> range;
    rep(i,H){
        rep(j,W-1){
            ll a = col[i][j], b = col[i][j+1];
            if(a==b) continue;
            if(a>b) swap(a,b);
            range.push_back(make_pair(b,a));
        }
    }
    rep(i,H-1){
        rep(j,W){
            ll a = col[i][j], b = col[i+1][j];
            if(a==b) continue;
            if(a>b) swap(a,b);
            range.push_back(make_pair(b,a));
        }
    }
    sort(range.begin(),range.end());
    ll end = 0;
    ll ans = 1;
    for(auto p:range){
        ll a = p.second, b = p.first;
        if(a>=end){
            ans++; end = b;
        }
    }
    cout << ans << endl;
}