#include<bits/stdc++.h>
#define N 1005
using namespace std;

int n,m,k,ans=0x3f3f3f3f;
int p1[N],p2[N],a[N],b[N],v[N][N],d[N][N];

int main(){
	cin>>n>>m>>k;
	for(int i=1,h1,h2,t1,t2;i<=n;i++){
		h1=h2=1;
		t1=t2=0;
		for(int j=1,x;j<=m;j++){
			if(p1[h1]==j-k)++h1;
			if(p2[h2]==j-k)++h2;
			cin>>x;
			while(a[t1]>=x&&t1>=h1)--t1;
			while(b[t2]<=x&&t2>=h2)--t2;
			a[++t1]=b[++t2]=x;
			p1[t1]=p2[t2]=j;
			v[i][j]=a[h1];
			d[i][j]=b[h2];
		}
	}
	for(int j=k,h1,h2,t1,t2;j<=m;j++){
		h1=h2=1;
		t1=t2=0;
		for(int i=1;i<=n;i++){
			if(p1[h1]==i-k)++h1;
			if(p2[h2]==i-k)++h2;
			while(a[t1]>=v[i][j]&&t1>=h1)--t1;
			while(b[t2]<=d[i][j]&&t2>=h2)--t2;
			a[++t1]=v[i][j];
			b[++t2]=d[i][j];
			p1[t1]=p2[t2]=i;
			if(i>=k)ans=min(ans,b[h2]-a[h1]);
		}
	}
	cout<<ans;
	return 0;
}