#include <bits/stdc++.h>
using namespace std;
const int N = 1000 + 10;
int a,b,n;
int ans = INT_MAX;
int num[N][N];
int maxn[N][N],minn[N][N],asmaxn[N][N],asminn[N][N];
int read(){
	char ch; int sum = 0,flag = 1;
	ch = getchar();
	while(ch < '0' || ch > '9'){if(ch == '-') flag = -flag; ch = getchar();}
	while(ch >= '0' && ch <= '9'){sum = sum * 10 + ch - '0'; ch = getchar();}
	return flag * sum;
}
int main(){
	memset(minn,0x3f3f3f3f,sizeof(minn));
	memset(asminn,0x3f3f3f3f,sizeof(asminn));
	a = read(); b = read(); n = read();
	for(int i = 1; i <= a; i++){
		for(int j = 1; j <= b; j++){
			num[i][j] = read();
		}
	}
	for(int i = 1; i <= a; i++){
		for(int j = 1; j + n - 1 <= b; j++){
			for(int k = 0; k < n; k++){
				maxn[i][j] = max(maxn[i][j],num[i][j + k]);
				minn[i][j] = min(minn[i][j],num[i][j + k]);
			}
		}
	}
	for(int i = 1; i + n - 1 <= a; i++){
		for(int j = 1; j + n - 1 <= b; j++){
			for(int k = 0; k < n; k++){
				asmaxn[i][j] = max(asmaxn[i][j],maxn[i + k][j]);
				asminn[i][j] = min(asminn[i][j],minn[i + k][j]);
			}
			ans = min(ans,asmaxn[i][j] - asminn[i][j]);
		}
	}
	printf("%d\n",ans);
	return 0;
}