#include<bits/stdc++.h>
#pragma GCC optimize(2)
#define ll long long
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=5010;
ll n,m,k,INF=1000000000;
ll w[N][N],minv[N][N];
ll maxv[N][N],que[N];
ll a[N],b[N],c[N],d[N];
void get_max(ll a[],ll f[],ll m){
    ll hh=0,tt=-1;
    for (register ll 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(ll a[], ll f[], ll m){
    ll hh =0,tt=-1;
	for(register ll 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 ll i=1;i<=n;++i){
    	for(register ll j=1;j<=m;++j){
    		w[i][j]=read();
		}      
	}
    for (register ll i=1;i<=n;++i){
        get_min(w[i],minv[i],m);
        get_max(w[i],maxv[i],m);
    }
    for (register ll i=k;i<=m;++i){
        for (register ll 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 ll j=k;j<=n;++j)INF=min(INF,c[j]-d[j]);
    }
   	cout<<INF;
    return 0;
}