#include <bits/stdc++.h>

#define REP(i,n) for (int i=0;i<(n);++i)

using namespace std;

using pii = pair<int, int>;

template <class T, class U> void amax(T& x, U y) {if (x < y) x = y;}

const int dx[] = {1, 0, -1, 0};
const int dy[] = {0, 1, 0, -1};

int main() {
    cin.tie(0);
    ios::sync_with_stdio(false);

    int H, W, N;
    cin >> H >> W >> N;
    vector<vector<int>> C(H, vector<int>(W));
    vector<vector<pii>> C_to_ij(N);
    REP(i, H) REP(j, W) {
        cin >> C[i][j];
        --C[i][j];
        C_to_ij[C[i][j]].emplace_back(i, j);
    }
    vector<int> C_to_D(N);
    REP(k, N) {
        if (k) {
            amax(C_to_D[k], C_to_D[k - 1]);
        }
        for (auto [i, j] : C_to_ij[k]) {
            REP(d, 4) {
                int ni = i + dx[d];
                int nj = j + dy[d];
                if (0 <= ni && ni < H && 0 <= nj && nj < W && C[i][j] < C[ni][nj]) {
                    amax(C_to_D[C[ni][nj]], C_to_D[k] + 1);
                }
            }
        }
    }
    int result = C_to_D[N - 1] + 1;
    cout << result << endl;

    return 0;
}