#include <iostream>

#include <cstdio>

#include <cmath>

using namespace std;

int a, b, n;

int tt;

int STn[][];

int STx[][];

int G[][];

int ans = 0x7f7f7f7f;

inline int Query(int x, int y)

{

    int maxx = , minn = ;

    maxx = max(STx[x][y], max(STx[x - (<<tt) + n][y], max(STx[x][y - (<<tt) + n], STx[x - (<<tt) + n][y - (<<tt) + n]))) ;

    minn = min(STn[x][y], min(STn[x - (<<tt) + n][y], min(STn[x][y - (<<tt) + n], STn[x - (<<tt) + n][y - (<<tt) + n]))) ;

    return maxx - minn;

}

int main()

{

    scanf("%d%d%d", &a, &b, &n);

    tt = log(n) / log();

    for (register int i =  ; i <= a ; i ++)

    {

        for (register int j =  ; j <= b ; j ++)

        {

            int x;scanf("%d", &x);G[i][j] = x;

            STn[i][j] = STx[i][j] = x;

        }

    }

    for (register int k =  ; k < tt ; k ++)

    {

        for (register int i =  ; i <= a ; i ++)

        {

            if (i + (<<k) > a) continue;

            for (register int j =  ; j <= b ; j ++)

            {

                if (j + (<<k) > b) continue;

                STn[i][j] = min(STn[i][j], min(STn[i + (<<k)][j + (<<k)], min(STn[i + (<<k)][j], STn[i][j + (<<k)])));

                STx[i][j] = max(STx[i][j], max(STx[i + (<<k)][j + (<<k)], max(STx[i + (<<k)][j], STx[i][j + (<<k)])));

            }

        }

    }

    for (register int i =  ; i <= a - n +  ; i ++)

    {

        for (register int j =  ; j <= b - n +  ; j ++)

        {

            ans = min(ans, Query(i, j));

        }

    }

    cout << ans;

    return ;

}