#include <bits/stdc++.h>
#define C__ const
using namespace std;
C__ int N_ = 1010, M_ = 110, L_ = __lg(M_) + 1, inf = 0x3f3f3f3f;
int a, b, n, g[N_][N_], ma[N_][N_], mi[N_][N_];
int main() {
	cin >> a >> b >> n;
	for (int i = 1; i <= a; i++)
		for (int j = 1; j <= b; j++) cin >> g[i][j];
	for (int i = 1; i <= a; i++) {
		deque<int> que;
		for (int j = 1; j <= b; j++) {
			while (!que.empty() && que.front() < j - n + 1) que.pop_front();
			while (!que.empty() && g[i][que.back()] < g[i][j]) que.pop_back();
			que.push_back(j);
			if (j - n + 1 > 0) ma[i][j - n + 1] = g[i][que.front()];
		}
		que.clear();
		for (int j = 1; j <= b; j++) {
			while (!que.empty() && que.front() < j - n + 1) que.pop_front();
			while (!que.empty() && g[i][que.back()] > g[i][j]) que.pop_back();
			que.push_back(j);
			if (j - n + 1 > 0) mi[i][j - n + 1] = g[i][que.front()];
		}
	}
	int ans = inf;
	for (int i = 1; i <= a - n + 1; i++) {
		for (int j = 1; j <= b - n + 1; j++) {
			int nowma = -inf, nowmi = inf;
			for (int k = 0; k < n; k++) {
				nowma = max(nowma, ma[i + k][j]);
				nowmi = min(nowmi, mi[i + k][j]);
			}
			ans = min(ans, nowma - nowmi);
		}
	}
	cout << ans << "\n";
	return 0;
}