#include<bits/stdc++.h>
#define int long long
using namespace std;
namespace IO{
	template<typename T> inline void read(T &x){
		bool f=1;x=0;char ch=getchar();
		while(ch<'0'||ch>'9'){if(ch=='-')f=0;ch=getchar();}
		while(ch>='0'&&ch<='9')x=(x<<1)+(x<<3)+(ch&15),ch=getchar();
		x=f?x:-x;
	}
	template<typename T> inline void write(T x){
		if(x<0) putchar('-'),x=-x;
	   	if(x>9) write(x/10);
	   	putchar(('0'+x%10));
	}
	template <typename T,typename ...Args> inline void read(T &x,Args &...args){read(x);read(args...);}
	template<typename T> inline void write(T x,char c){write(x),putchar(c);}
}
using namespace IO;
int a,b,n,m[1005][1005],ans=INT_MAX;
int maxn[1005][1005],minn[1005][1005];
signed main(){
	read(a,b,n);
	for(int i=0;i<a;++i)
		for(int j=0;j<b;++j){
			read(m[i][j]);
			maxn[i][j]=minn[i][j]=m[i][j];
		}
	
	for(int k=2;k<=n;++k)
		for(int i=0;i+1<a;++i)
			for(int j=0;j+1<b;++j){
				maxn[i][j]=max(m[i][j],max(maxn[i+1][j+1],max(maxn[i+1][j],maxn[i][j+1])));
				minn[i][j]=min(m[i][j],min(minn[i+1][j+1],min(minn[i+1][j],minn[i][j+1])));
			}
	for(int i=0;i<=a-n;++i)
		for(int j=0;j<=b-n;++j)ans=min(ans,maxn[i][j]-minn[i][j]);
	write(ans);
	return 0;
}