#include<bits/stdc++.h>
#include<atcoder/all>
using namespace std;
using namespace atcoder;
#define rep(i,n)for (int i = 0; i < int(n); ++i)
#define rrep(i,n)for (int i = int(n)-1; i >= 0; --i)
#define all(x) (x).begin(), (x).end()
#define rall(x) (x).rbegin(), (x).rend()
template<class T> void chmax(T& a, const T& b) {a = max(a, b);}
template<class T> void chmin(T& a, const T& b) {a = min(a, b);}
using ll = long long;
using P = pair<int,int>;
using VI = vector<int>;
using VVI = vector<VI>;
using VL = vector<ll>;
using VVL = vector<VL>;

int main() {
    ios::sync_with_stdio(false);
    cin.tie(0);
    int h, w, n;
    cin >> h >> w >> n;
    VVI c(h, VI(w));
    rep(i, h) rep(j, w) cin >> c[i][j], c[i][j]--;
    VVI to(n);
    rep(i, h - 1) rep(j, w) {
        int x = c[i][j], y = c[i + 1][j];
        if (x < y) to[x].push_back(y);
        else if (x > y) to[y].push_back(x);
    }
    rep(i, h) rep(j, w - 1) {
        int x = c[i][j], y = c[i][j + 1];
        if (x < y) to[x].push_back(y);
        else if (x > y) to[y].push_back(x);
    }
    VI dp(n);
    rep(i, n) {
        for(int j: to[i]) chmax(dp[j], dp[i] + 1);
        if (i + 1 < n) chmax(dp[i + 1], dp[i]);
    }
    int ans = *max_element(all(dp)) + 1;
    cout << ans << endl;
}