大样例3没过，但是5e5太大了，调不出来，求一个小一点的hack数据或者帮蒟蒻调一调。谢谢！！！

#include <iostream>
#include <cstdio>
#include <cstring>
#include <algorithm>
#include <vector>
#include <cmath>
using namespace std;
#define int long long 
inline int read(){
	register int x=0,f=0,ch=getchar();
	while('0'>ch||ch>'9')f^=ch=='-',ch=getchar();
	while('0'<=ch&&ch<='9')x=x*10+(ch^'0'),ch=getchar();
	return f?-x:x;
}
const int MAX=6e6+5;
int n,m;
struct E{int op,v,id;}a[MAX];
inline int cmp(const E & x,const E & y){
	return x.v < y.v;
}
int vis[MAX],pre[MAX],suf[MAX];
int buc[MAX],pas[MAX]; 
signed main(){
//	freopen("in.in","r",stdin);
	memset(pas,0x3f,sizeof(pas));
	n=read(),m=read();
	for(register int i=1;i<=n;++i)a[i].op=0,a[i].v=read(),a[i].id=i;
	for(register int i=n+1;i<=n+n;++i)a[i].op=1,a[i].v=read(),a[i].id=i-n;
	sort(a+1,a+1+n+n,cmp); 
	for(register int i=1;i<=n+n;++i)pre[i] = pre[i-1] + (a[i].op == 1);
	for(register int i=n+n;i;--i){
		suf[i] = suf[i+1] + (a[i].op == 1);
		pas[a[i].id] = min(pas[a[i].id],i); 
//		printf("%d : %d %d %d\n",i,a[i].v,a[i].id,a[i].op);
	}
//	puts("");
	
	int ans=0x3f3f3f3f3f3f3f3f,high=n+n,L=0;
	while (L<n+n && !buc[a[L+1].id])++L,buc[a[L].id]=1;
	memset(buc,0,sizeof(buc));
	for(register int i=n+n;i>=1;--i){
		int l=1,r=min(L+1,high),pos=-1;
		while (l<=r){
			int mid=l+r>>1;
			if(pre[mid-1] + suf[i+1] <=m) l=mid+1, pos=mid;
			else r=mid-1; 
		}
		if(pos != -1)ans = min (ans,a[i].v - a[pos].v);
		if(buc[a[i].id])break;
		++buc[a[i].id];
		high=min(high,pas[a[i].id]);
		high=min(high,i-1); 
	}
	printf("%lld\n",ans);
	return 0;
}