#define _USE_MATH_DEFINES
#include <bits/stdc++.h>
using namespace std;
#define FOR(i,m,n) for(int i=(m);i<(n);++i)
#define REP(i,n) FOR(i,0,n)
#define ALL(v) (v).begin(),(v).end()
using ll = long long;
constexpr int INF = 0x3f3f3f3f;
constexpr long long LINF = 0x3f3f3f3f3f3f3f3fLL;
constexpr double EPS = 1e-8;
constexpr int MOD = 1000000007;
// constexpr int MOD = 998244353;
constexpr int dy[] = {1, 0, -1, 0}, dx[] = {0, -1, 0, 1};
constexpr int dy8[] = {1, 1, 0, -1, -1, -1, 0, 1}, dx8[] = {0, -1, -1, -1, 0, 1, 1, 1};
template <typename T, typename U> inline bool chmax(T &a, U b) { return a < b ? (a = b, true) : false; }
template <typename T, typename U> inline bool chmin(T &a, U b) { return a > b ? (a = b, true) : false; }
struct IOSetup {
  IOSetup() {
    std::cin.tie(nullptr);
    std::ios_base::sync_with_stdio(false);
    std::cout << fixed << setprecision(20);
  }
} iosetup;

int main() {
  int h, w, n; cin >> h >> w >> n;
  vector c(h, vector(w, 0)); REP(i, h) REP(j, w) cin >> c[i][j], --c[i][j];
  vector<int> v(n, n);
  auto f = [&](int a, int b) -> void {
    if (a == b) return;
    if (a > b) swap(a, b);
    chmin(v[a], b);
  };
  REP(i, h) REP(j, w) {
    if (i + 1 < h) f(c[i][j], c[i + 1][j]);
    if (j + 1 < w) f(c[i][j], c[i][j + 1]);
  }
  int ans = 0;
  for (int i = 0; i < n;) {
    ++ans;
    int dis = n;
    for (; i < dis; ++i) chmin(dis, v[i]);
  }
  cout << ans << '\n';
  return 0;
}