#include <bits/stdc++.h>
using namespace std;

const int MAXN = 10;
const int MAXA = 110;
const int MAXB = 110;
const int INF = 0x3f3f3f3f;
int n, A, B;
int a[MAXA][MAXB];
int ans = INF;

int main(int, char const *[])
{
  ios::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);
  cin >> A >> B >> n;
  for (int i = 1; i <= A; i++)
    for (int j = 1; j <= B; j++)
      cin >> a[i][j];
  for (int i = 1; i <= A - n + 1; i++)
    for (int j = 1; j <= B - n + 1; j++)
    {
      int maxn = -INF, minn = INF;
      for (int x = i; x <= i + n - 1; x++)
        for (int y = j; y <= j + n - 1; y++)
        {
          maxn = max(maxn, a[x][y]);
          minn = min(minn, a[x][y]);
        }
      ans = min(ans, maxn - minn);
    }
  cout << ans << endl;
  return 0;
}