//P2216
#include<bits/stdc++.h>
using namespace std;
const int N=1009;
int n,m,x,a[N][N];
int q1[N],q2[N],h1=1,t1=0,h2=1,t2=0,mn[N][N],mx[N][N];//q[i] [i,i+x-1]
int ans=INT_MAX;
int main()
{
	cin>>n>>m>>x;
	for(int i=1;i<=n;i++)
		for(int j=1;j<=m;j++)
			scanf("%d",&a[i][j]);
	
	for(int i=1;i<=n;i++){
		h1=h2=1,t1=t2=0;
		for(int j=1;j<=m;j++){
			while(h1<=t1&&q1[h1]<j-x+1)h1++;
			while(h1<=t1&&a[i][q1[t1]]>=a[i][j])t1--;
			q1[++t1]=j;
			if(j>=x)mn[i][j-x+1]=a[i][q1[h1]];
			
			while(h2<=t2&&q2[h2]<j-x+1)h2++;
			while(h2<=t2&&a[i][q2[t2]]<=a[i][j])t2--;
			q2[++t2]=j;
			if(j>=x)mx[i][j-x+1]=a[i][q2[h2]];
//			cout<<a[i][q1[h1]]<<' '<<a[i][q2[h2]]<<"||";
		}
//		cout<<endl;
	}
	
//	for(int i=1;i<=n;i++){
//		for(int j=1;j<=m-x+1;j++)cout<<mn[i][j]<<' '<<mx[i][j]<<endl;
//	}
	
	for(int j=1;j<=m-x+1;j++){
		h1=h2=1,t1=t2=0;
		for(int i=1;i<=n;i++){
			while(h1<=t1&&q1[h1]<i-x+1)h1++;
			while(h1<=t1&&mn[q1[t1]][j]>=mn[i][j])t1--;
			q1[++t1]=i;
			
			while(h2<=t2&&q2[h2]<i-x+1)h2++;
			while(h2<=t2&&mx[q2[t2]][j]<=mx[i][j])t2--;
			q2[++t2]=i;
			if(i>=x)ans=min(ans,mx[q2[h2]][j]-mn[q1[h1]][j]);
		}
	}
	cout<<ans;
}