#include <cstdio>
#include <cstring>
#include <iostream>
#include <cctype>
#include <algorithm>
#include <cmath>
using namespace std;#define res register int
#define getchar gc
char buf[1<<18],*fc,*tc;
inline char gc()
{if(fc==tc){tc=(fc=buf)+fread(buf,1,1<<18,stdin);if(tc==fc) return EOF;}return *fc++;
}
inline int read()
{int x=0,f=1; char ch;while(!isdigit(ch=getchar())) if(ch=='-') f=-1;while(isdigit(ch)) x=x*10+ch-'0',ch=getchar();return f*x;
}const int N=1005,inf=0x3f3f3f3f;
int a,b,n;
int mp[N][N],X[N][N],x[N][N],Y[N][N],y[N][N];
//大写最大值，小写最小值
//x[i][j]:第i行j~j+n-1的最小值
//y[i][j]:从mp[i~i+n-1][j~j+n-1]的最小值 int Q[N],q[N],h,t,H,T;//head -> tail  单调  inline void solve()
{for(res i=1 ; i<=a ; ++i){h=t=H=T=Q[1]=q[1]=1;for(res j=2 ; j<=b ; ++j){while(H<=T&&mp[i][j]>=mp[i][Q[T]]) --T;//维护单调性 while(h<=t&&mp[i][j]<=mp[i][q[t]]) --t;q[++t]=j; Q[++T]=j;    //维护大小 while(j-Q[H]>=n) ++H;  while(j-q[h]>=n) ++h;if(j>=n) X[i][j-n+1]=mp[i][Q[H]],x[i][j-n+1]=mp[i][q[h]]; }}for(res j=1 ; j+n-1<=b ; ++j)//维护j~j+n-1列 {h=t=H=T=Q[1]=q[1]=1;for(res i=2 ; i<=a ; ++i){while(H<=T&&X[i][j]>=X[Q[T]][j]) --T;while(h<=t&&x[i][j]<=x[q[t]][j]) --t;Q[++T]=i; q[++t]=i;while(i-Q[H]>=n) ++H;while(i-q[h]>=n) ++h;if(i>=n) Y[i-n+1][j]=X[Q[H]][j],y[i-n+1][j]=x[q[h]][j];}}
}int main()
{a=read(); b=read(); n=read();for(res i=1 ; i<=a ; ++i) for(res j=1 ; j<=b ; ++j) mp[i][j]=read();solve();int ans=inf;for(res i=1 ; i+n-1<=a ; ++i)for(res j=1 ; j+n-1<=b ; ++j)ans=min(ans,Y[i][j]-y[i][j]);printf("%d\n",ans);return 0;
}