#include<iostream>

#include<cstdio>

#include<cstring>

#include<algorithm>

#define maxn 1050

#define inf 2000000000

using namespace std;

int n,m,a,map[maxn][maxn],m1[maxn][maxn][],m2[maxn][maxn][],q1[maxn],q2[maxn],l1,r1,l2,r2,ans=inf;

void get_m1()

{

    for (int i=;i<=n;i++)

    {

        l1=l2=;r1=r2=;

        for (int j=m;j>=;j--)

        {

            while ((l1<=r1) && (q1[l1]>=j+a)) l1++;

            while ((l2<=r2) && (q2[l2]>=j+a)) l2++;

            while ((l1<=r1) && (map[i][j]>map[i][q1[r1]])) r1--;

            while ((l2<=r2) && (map[i][j]<map[i][q2[r2]])) r2--;

            q1[++r1]=j;q2[++r2]=j;

            m1[i][j][]=map[i][q1[l1]];m1[i][j][]=map[i][q2[l2]];

        }

    }

}

void get_m2()

{

    for (int i=;i<=m;i++)

    {

        l1=l2=;r1=r2=;

        for (int j=n;j>=;j--)

        {

            while ((l1<=r1) && (q1[l1]>=j+a)) l1++;

            while ((l2<=r2) && (q2[l2]>=j+a)) l2++;

            while ((l1<=r1) && (m1[j][i][]>m1[q1[r1]][i][])) r1--;

            while ((l2<=r2) && (m1[j][i][]<m1[q2[r2]][i][])) r2--;

            q1[++r1]=j;q2[++r2]=j;

            m2[j][i][]=m1[q1[l1]][i][];m2[j][i][]=m1[q2[l2]][i][];

        }

    }

}

int main()

{

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

    for (int i=;i<=n;i++)

        for (int j=;j<=m;j++)

            scanf("%d",&map[i][j]);

    get_m1();

    get_m2();

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

        for (int j=;j<=m-a+;j++)

            ans=min(ans,m2[i][j][]-m2[i][j][]);

    printf("%d\n",ans);

    return ;

}