#include<bits/stdc++.h>
#pragma GCC optimize(2)
using namespace std;
long long read(){
	long long x=0,f=1;char ch=getchar();
	while(ch<'0'||ch>'9'){
		if(ch=='-')f=-1;
		ch=getchar();
	}
	while(ch>='0'&&ch<='9'){
		x=x*10+ch-'0';
		ch=getchar();
	}
	return x*f;
}
const int N=1010;
int n,m,k,INF=0x3f3f3f3f;
int w[N][N],minv[N][N];
int maxv[N][N],que[N];
int a[N],b[N],c[N],d[N];
void get_max(int a[],int f[],int m){
    int hh=0,tt=-1;
    for (int i=1;i<=m;i++){
        while(hh<=tt&&i-que[hh]>=k) hh++;
		while(hh<=tt&&a[i]>=a[que[tt]]) tt--;
		que[++tt]=i;
		f[i]=a[que[hh]];
	}
}
void get_min(int a[], int f[], int m){
    int hh =0,tt=-1;
	for(int i=1;i<=m;i++){
		while(hh<=tt&&i-que[hh]>=k)hh++;
		while(hh<=tt&&a[i]<=a[que[tt]])tt--;
		que[++tt]=i;
 		f[i]=a[que[hh]];
    }
}
int main(){	
	n=read();
	m=read();
	k=read();
    for (register int i=1;i<=n;i++){
    	for(register int j=1;j<=m;j++){
    		w[i][j]=read();
		}      
	}
    for (register int i=1;i<=n;i++){
        get_min(w[i],minv[i],m);
        get_max(w[i],maxv[i],m);
    }
    for (register int i=k;i<=m;i++){
        for (register int j=1;j<=n;j++){
            a[j]=maxv[j][i];
            b[j]=minv[j][i];
        }
        get_max(a,c,n);
        get_min(b,d,n);
        for(register int j=k;j<=n;j++)INF=min(INF,c[j]-d[j]);
    }
   	cout<<INF<<endl;
    return 0;
}