#include <bits/stdc++.h>
#define pos  first
#define d	second
#define pii  pair<int,int> 
#define inf  0x7f7f7f7f
#define mp   make_pair 
using namespace std;
int a,b,n;
int p[1005][1005],ans=inf;
int M[1005][1005],m[1005][1005],p1[1005],p2[1005];
int main(){
	cin>>a>>b>>n;
	for(int i=1;i<=a;i++)
	for(int j=1;j<=b;j++)
	{
		scanf("%d",&p[i][j]);
		M[i][j]=m[i][j]=p[i][j];
	}
	for(int i=1;i<=a;i++)
	{
		int l1=1,l2=1;int r1=0,r2=0;
		for(int j=1;j<=b;j++)
		{
			while(l1<=r1&&j-p1[l1]>=n) l1++;
			while(l2<=r2&&j-p2[l2]>=n) l2++;
			while(l1<=r1&&p[i][j]>p[i][p1[r1]]) r1--;
			while(l2<=r2&&p[i][j]<p[i][p2[r2]]) r2--;
			p1[++r1]=j;M[i][j]=max(M[i][j],p[i][p1[l1]]);
			p2[++r2]=j;m[i][j]=min(m[i][j],p[i][p2[l2]]);
		}
	}
	for(int i=n;i<=b;i++)
    {
        int l1=1,l2=1;int r1=0,r2=0;
        for(int j=1;j<=a;j++)
        {
			while(l1<=r1&&j-p1[l1]>=n) l1++;
			while(l2<=r2&&j-p2[l2]>=n) l2++;
			while(l1<=r1&&M[j][i]>M[p1[r1]][i]) r1--;
			while(l2<=r2&&m[j][i]<m[p2[r2]][i]) r2--;
			p1[++r1]=j;p2[++r2]=j;
			if(j>=n) ans=min(ans,M[p1[l1]][i]-m[p2[l2]][i]);
		}
	}
    printf("%d",ans);
    return 0;
}