#include <bits/stdc++.h>
using namespace std;
int n, m, k;
int q[5010];
int w[5010][5010], row_min[5010][5010], row_max[5010][5010];
void get_min(int a[], int b[], int tot)
{
   int _head = 0, _tail = -1;
   for (int i = 1; i <= tot; i++)
   {
      if (_head <= _tail && q[_head] <= i - k)
         _head++;
      while (_head <= _tail && a[q[_tail]] >= a[i])
         _tail--;
      q[++_tail] = i;
      b[i] = a[q[_head]];
   }
}
void get_max(int a[], int b[], int tot)
{
   int _head = 0, _tail = -1;
   for (int i = 1; i <= tot; i++)
   {
      if (_head <= _tail && q[_head] <= i - k)
         _head++;
      while (_head <= _tail && a[q[_tail]] <= a[i])
         _tail--;
      q[++_tail] = i;
      b[i] = a[q[_head]];
   }
}
int main()
{
   cin >> n >> m >> k;
   for (int i = 1; i <= n; i++)
      for (int j = 1; j <= m; j++)
         cin >> w[i][j];
   for (int i = 1; i <= n; i++)
   {
      get_min(w[i], row_min[i], m);
      get_max(w[i], row_max[i], m);
   }
   int res = 1000000009;
   int a[5010], b[5010], c[5010];
   for (int i = k; i <= m; i++)
   {
      for (int j = 1; j <= n; j++)
         a[j] = row_min[j][i];
      get_min(a, b, n);
      for (int j = 1; j <= n; j++)
         a[j] = row_max[j][i];
      get_max(a, c, n);
      for (int j = k; j <= n; j++)
         res = min(res, c[j] - b[j]);
   }
   cout << res << endl;
   return 0;
}