#include <bits/stdc++.h>
#define endl "\n"
using namespace std;
typedef long long ll;
typedef vector<ll> vl;
typedef pair<ll, ll> PP;
#pragma GCC optimize("O3")
#pragma GCC optimize("unroll-loops")
#pragma GCC target("avx")
#pragma comment(linker, "/stack:200000000")
#define overload4(_1, _2, _3, _4, name, ...) name
#define overload3(_1, _2, _3, name, ...) name
#define rep1(n) for (ll i = 0; i < n; ++i)
#define rep2(i, n) for (ll i = 0; i < n; ++i)
#define rep3(i, a, b) for (ll i = a; i < b; ++i)
#define rep4(i, a, b, c) for (ll i = a; i < b; i += c)
#define rep(...) overload4(__VA_ARGS__, rep4, rep3, rep2, rep1)(__VA_ARGS__)
#define rrep1(n) for (ll i = n; i--;)
#define rrep2(i, n) for (ll i = n; i--;)
#define rrep3(i, a, b) for (ll i = b; i-- > (a);)
#define rrep4(i, a, b, c)                                                      \
  for (ll i = (a) + ((b) - (a)-1) / (c) * (c); i >= (a); i -= c)
#define rrep(...)                                                              \
  overload4(__VA_ARGS__, rrep4, rrep3, rrep2, rrep1)(__VA_ARGS__)
#define elif else if
ll beki(ll i) { return 1ll << i; }
#define skip(M)                                                                \
  if (M)                                                                       \
  continue
#define all(v) v.begin(), v.end()
#define allm(x, y, M) for (auto [(x), (y)] : (M))
#define alls(i, S) for (auto(&i) : (S))
#define pb push_back
#define fi first
#define se second
const ll INF = (1LL << 61) - 1;
const ll MOD = 1000000007;
const ll MOD2 = 998244353;
const ll MAX_N1 = 200010;
const ll MAX_N2 = 500010;
template <class X> void print(X x) { cout << x << endl; }
void print(vl x) {
  for (ll i : x) {
    cout << i << " ";
  }
  cout << endl;
}
void print(vector<PP> x) {
  for (PP i : x) {
    cout << i.first << " " << i.second << endl;
  }
  cout << endl;
}
template <class X> void printr(X x) { cerr << x << endl; }
void printr(vl x) {
  for (ll i : x) {
    cerr << i << " ";
  }
  cerr << endl;
}
void printr(vector<PP> x) {
  for (PP i : x) {
    cerr << i.first << " " << i.second << endl;
  }
  cout << endl;
}
template <class X> int lbound(vector<X> &Y, X a) {
  return lower_bound(all(Y), a) - Y.begin();
}
template <class X> int ubound(vector<X> &Y, X a) {
  return upper_bound(all(Y), a) - Y.begin();
}
template <class X> X lbound2(vector<X> &Y, X a, int mode = 0) {
  int x = lbound(Y, a) - mode;
  if (x < 0 || x >= Y.size())
    return INF;
  return Y[x];
}
template <class X> X ubound2(vector<X> &Y, X a, int mode = 0) {
  int x = ubound(Y, a) - mode;
  if (x < 0 || x >= Y.size())
    return INF;
  return Y[x];
}
template <class... T> void cl(T &... t) { (..., (t.clear())); }
template <class... T> void in(T &... t) { (..., (cin >> t)); }
template <class... T> void put(vl &V, int n, int mode = 0) {
  ll k;
  if (mode == 0)
    cl(V);
  rep(i, n) {
    cin >> k;
    V.pb(k);
  }
}
int max_index(vl &V) { return max_element(all(V)) - V.begin(); }
int min_index(vl &V) { return min_element(all(V)) - V.begin(); }
ll sum(vl &V) { return accumulate(all(V), 0ll); }
template <typename T> void UNIQUE(vector<T> &v) {
  sort(v.begin(), v.end());
  v.erase(unique(v.begin(), v.end()), v.end());
}
template <typename T> T ADD(T a, T b) {
  T res;
  return __builtin_add_overflow(a, b, &res) ? numeric_limits<T>::max() : res;
}
template <typename T> T MUL(T a, T b) {
  T res;
  return __builtin_mul_overflow(a, b, &res) ? numeric_limits<T>::max() : res;
};
template <typename T> T POW(T a, int n) {
  T res = 1;
  for (; n > 0; n >>= 1, a *= a)
    if (n & 1)
      res *= a;
  return res;
}
template <class X> bool ma(X &a, X b) {
  if (a < b) {
    a = b;
    return true;
  }
  return false;
}
template <class X> bool mi(X &a, X b) {
  if (a > b) {
    a = b;
    return true;
  }
  return false;
}
void vset(vl &A, ll n, ll k) { A = vl(n, k); }
void so(vl &A) { sort(all(A)); }
ll age(ll x, ll y) { return (x + y - 1) / y; }
ll a, b, c, d, aa, bb, cc, dd, h, x, y, z, p, q, n, t, r, k, w, l, ans, m, u, v;
ll codeforces = 1;
string S, T, U;
vl A, B, C, D;
vl g[MAX_N2];
vector<PP> VP, VP2;
set<ll> s1, s2;
class UnionFind {
  // まとめる 判定 サイズを知る
public:
  // Aから見た親の番号を格納する。rootだったら-1*その集合のサイズ。
  vector<int> Parent;

  // 初期化
  UnionFind(ll N) { Parent = vector<int>(N, -1); }

  // Aのrootを調べる
  int root(int A) {
    if (Parent[A] < 0)
      return A; // マイナスならそれはroot
    return Parent[A] = root(Parent[A]);
  }

  // rootの値をプラスに戻して返す(サイズ)
  ll size(int A) { return -Parent[root(A)]; }

  // くっつける関数
  bool connect(int A, int B) {
    // AとBのroot同士をくっつける
    A = root(A); // ここのAは、"rootの場所"の意味
    B = root(B);
    if (A == B)
      return false; // 既にくっついている
    if (size(A) < size(B))
      swap(A, B); // 大きい方にくっつけるために中身交換
    Parent[A] += Parent[B]; // 中身更新
    Parent[B] = A;
    return true;
  }
};
void solve() {
  in(h, w, n);
  UnionFind UNI(h * w);
  vector<tuple<ll, ll, ll>> TT;
  vector<PP> TTT[h * w];
  ll masu[h][w], saisyou[h * w];
  rep(i, h) {
    rep(j, w) {
      in(masu[i][j]);
      TTT[masu[i][j] - 1].pb({i, j});
      saisyou[i * w + j] = -1;
      TT.push_back({masu[i][j], i, j});
    }
  }
  rep(i, h * w) {
    p = TTT[i].size();
    rep(j, p - 1) {
      auto [aa, bb] = TTT[i][j];
      auto [cc, dd] = TTT[i][j + 1];
      UNI.connect(aa * w + bb, cc * w + dd);
    }
  }
  sort(all(TT));
  k = 0;
  rep(i, h * w) {
    auto [a, b, c] = TT[i];
    saisyou[b * w + c] = max(1ll, k);
    if (b) {
      if (masu[b - 1][c] == masu[b][c]) {
        UNI.connect((b - 1) * w + c, b * w + c);
      } else if (saisyou[UNI.root((b - 1) * w + c)] > 0)
        ma(saisyou[UNI.root(b * w + c)],
           saisyou[UNI.root((b - 1) * w + c)] + 1);
    }
    if (c) {
      if (masu[b][c - 1] == masu[b][c]) {
        UNI.connect((b)*w + c - 1, b * w + c);
      } else if (saisyou[UNI.root((b)*w + c - 1)] > 0)
        ma(saisyou[UNI.root(b * w + c)], saisyou[UNI.root((b)*w + c - 1)] + 1);
    }
    if (b < h - 1) {
      if (masu[b + 1][c] == masu[b][c]) {
        UNI.connect((b + 1) * w + c, b * w + c);
      } else if (saisyou[UNI.root((b + 1) * w + c)] > 0)
        ma(saisyou[UNI.root(b * w + c)],
           saisyou[UNI.root((b + 1) * w + c)] + 1);
    }
    if (c < w - 1) {
      if (masu[b][c + 1] == masu[b][c]) {
        UNI.connect((b)*w + c + 1, b * w + c);
      } else if (saisyou[UNI.root((b)*w + c + 1)] > 0)
        ma(saisyou[UNI.root(b * w + c)], saisyou[UNI.root((b)*w + c + 1)] + 1);
    }
    k = saisyou[UNI.root(b * w + c)];
  }

  rep(i, h) {
    rep(j, w) { ma(ans, saisyou[i * w + j]); }
  }
  print(ans);
}
int main() {
  cout << fixed << setprecision(15);
  cin.tie(0);
  ios::sync_with_stdio(false);
  // cin >> codeforces;
  while (codeforces--) {
    ans = 0;
    solve();
  }
}