#include<iostream>
#include<algorithm>
#include<cstdio>
using namespace std;
int a,b,n,ans=0x3fffffff;
int as[1005][1005],Maxh[1005][1005],Minh[1005][1005];
int x1,x2,y1,y2,q1[1005],q2[1005]; 
int Maxz[1005][1005],Minz[1005][1005];
int main()
{
	cin>>a>>b>>n;
	for(int i=1;i<=a;i++)
	{
		for(int j=1;j<=b;j++) cin>>as[i][j];
	}
	for(int i=1;i<=a;i++)
	{
		x1=x2=y1=y2=1;
		for(int j=1;j<=b;j++)
		{
			while(x1<y1&&j-q1[x1]>=n) x1++;
			while(x2<y2&&j-q2[x2]>=n) x2++;
			while(x1<y1&&as[i][q1[y1-1]]<=as[i][j]) y1--;
			while(x2<y2&&as[i][q2[y2-1]]>=as[i][j]) y2--;
			q1[y1++]=j;
			q2[y2++]=j;
			if(j>=n)
			{
				Maxh[i][j-n+1]=as[i][q1[x1]];
				Minh[i][j-n+1]=as[i][q2[x2]];
			 } 
		}
	}
	for(int i=1;i<=b-n+1;i++)
	{
		x1=x2=y1=y2=1;
		for(int j=1;j<=a;j++)
		{
			while(x1<y1&&j-q1[x1]>=n) x1++;
			while(x2<y2&&j-q2[x2]>=n) x2++;
			while(x1<y1&&Maxh[q1[y1-1]][i]<=Maxh[j][i]) y1--;
			while(x2<y2&&Minh[q2[y2-1]][i]>=Minh[j][i]) y2--;
			q1[y1++]=j;
			q2[y2++]=j;
			if(j>=n)
			{
				Maxz[j-n+1][i]=Maxh[q1[x1]][i];
				Minz[j-n+1][i]=Minh[q2[x2]][i];
			 } 
		}
	}
	for(int i=1;i<=a-n+1;i++)
	{
		for(int j=1;j<=b-n+1;j++) ans=min(ans,Maxz[i][j]-Minz[i][j]);
	}
	cout<<ans;
	return 0;
}