#include<iostream>
#include<cstdio>
#include<algorithm>
using namespace std;
const int N = 1005;
const int inf = 1e9;
struct node{int i,v;};
int f[N][N],a,b,n,ans=inf,lc[2][N],rc[2][N];
int maxx[N],minn[N],st[2],ed[2];
node qc[2][N][N],q[2][N];
int main() 
{
    scanf("%d%d%d",&a,&b,&n);
    for(int i=1;i<=a;i++)
      for(int j=1;j<=b;j++)scanf("%d",&f[i][j]);
    for(int i=1;i<=b;i++)lc[0][i]=lc[1][i]=1;
    int ii=0;
    for(int i=n;i<=a;i++)
    {   
        //push_back
        while(ii+1<=i)
        {
            ii++;
            for(int j=1;j<=b;j++)
            {
                int v=f[ii][j];
                while(lc[0][j]<=rc[0][j]&&v<=qc[0][j][rc[0][j]].v)rc[0][j]--;
                qc[0][j][++rc[0][j]]=(node){ii,v};
                while(lc[1][j]<=rc[1][j]&&v>=qc[1][j][rc[1][j]].v)rc[1][j]--;
                qc[1][j][++rc[1][j]]=(node){ii,v};
            }
        }

        //pop
        for(int j=1;j<=b;j++)
        {
            while(lc[0][j]<=rc[0][j]&&qc[0][j][lc[0][j]].i<=i-n)lc[0][j]++;
            while(lc[1][j]<=rc[1][j]&&qc[1][j][lc[1][j]].i<=i-n)lc[1][j]++;
        }
        for(int j=1;j<=b;j++)
            minn[j]=qc[0][j][lc[0][j]].v,maxx[j]=qc[1][j][lc[1][j]].v;

        st[0]=st[1]=1;
        ed[0]=ed[1]=0;
        int k=0;
        for(int j=n;j<=b;j++)
        {
            while(k+1<=j)
            {
                k++;
                while(st[0]<=ed[0]&&maxx[k]>=q[0][ed[0]].v)ed[0]--;
                q[0][++ed[0]]=(node){k,maxx[k]};
                while(st[1]<=ed[1]&&minn[k]<=q[1][ed[1]].v)ed[1]--;
                q[1][++ed[1]]=(node){k,minn[k]};
            }
            while(st[0]<=ed[0]&&q[0][st[0]].i<=j-n)st[0]++;
            while(st[1]<=ed[1]&&q[1][st[1]].i<=j-n)st[1]++;
            ans=min(ans,q[0][st[0]].v-q[1][st[1]].v);
        }

    }
    printf("%d",ans);
	return 0;
}