//xiaozhoulaoshi:bits/stdc++.h banned
#include"cstdio"
#include"iostream"
#include"cstdlib"
using namespace std;
//xiaozhoulaoshi:no variable names such as a,b,c
int x=0,y=0,n=0,maxn=0,minn=0,ans=0;
int scan[1002][1002];
int xmax[1002][1002],ymax[1002][1002];
int xmin[1002][1002],ymin[1002][1002];
int main()
{
	//xiaozhoulaoshi:chushihua 
	for (int i=1;i<=1001;i++)
{
	for (int j=1;j<=1001;j++)
	{
		scan[i][j]=0;
		xmax[i][j]=0;
		xmin[i][j]=0;
		ymax[i][j]=0;
		ymin[i][j]=0;
	}
}
	scanf("%d%d%d",&x,&y,&n);
	for (int i=1;i<=x;i++)
	{
		for (int j=1;j<=y;j++)
		{
			scanf("%d",&scan[i][j]);
		}
	}
	for (int i=1;i<=(x-n+1);i++)
	{
		for (int j=1;j<=y;j++)
		{
			maxn=0;
			minn=1145141919;
			for (int p=1;p<=n;p++)
			{
				xmax[i][j]=max(maxn,scan[(i+p-1)][j]);
				xmin[i][j]=min(minn,scan[(i+p-1)][j]);
			}
		}
	}
	for (int i=1;i<=(x-n+1);i++)
	{
		for (int j=1;j<=(y-n+1);j++)
		{
			maxn=0;
			minn=1145141919;
			for (int p=1;p<=n;p++)
			{
				ymax[i][j]=max(maxn,xmax[i][(j+p-1)]);
				ymin[i][j]=min(minn,xmin[i][(j+p-1)]);
			}
		}
	}
	for (int i=1;i<=(x-n+1);i++)
	{
		for (int j=1;j<=(y-n+1);j++)
		{
			ans=max(ans,(ymax[i][j]-ymin[i][j]));
		}
	}
	printf("%d",ans);
	return 0;
}
```cpp