真正的萌新求助，不知道为什么MLEorz

#include <iostream>
#include <cstdio>
#include <algorithm>
using namespace std;

struct node{
	int lc,rc,valu,pri,cnt,sze;
	#define lc(x)t[x].lc
	#define rc(x)t[x].rc
	#define v(x)t[x].valu
	#define p(x)t[x].pri
	#define c(x)t[x].cnt
	#define s(x)t[x].sze
}t[100100];

int n,tot,root;

void upt(int k)
{
	s(k)=s(lc(k))+s(rc(k))+c(k);
}

void zig(int &k)
{
	int y=rc(k);
	int x=lc(y);
	rc(k)=x;
	lc(y)=k;
	s(y)=s(k);
	upt(k);
	k=y;
}

void zag(int &k)
{
	int y=lc(k);
	int x=rc(y);
	lc(k)=x;
	rc(y)=k;
	s(y)=s(k);
	upt(k);
	k=y;
}

void Insert(int &k,int key){
	if (!k){
		k=++tot;
		v(k)=key;
		p(k)=rand();
		c(k)=s(k)=1;
		lc(k)=rc(k)=0;
		return;
	}
	++s(k);
	if (v(k)==key) ++c(k);
	else{
		if (key<v(k)){
			Insert(lc(k),key);
			if (p(lc(k))<p(k)) zag(k);
		}
		else{
			Insert(rc(k),key);
			if (p(rc(k))<p(k)) zig(k);
		}
	}
	return;
}

void Delete(int &k,int key){
	if (v(k)==key){
		if (c(k)>1) --c(k),--s(k);
		else if (!lc(k)||!rc(k)) k=lc(k)+rc(k);
			else if (p(lc(k))<p(rc(k))) zag(k),Delete(k,key);
				else zig(k),Delete(k,key);
	}
	--s(k);
	if (key<v(k)) Delete(lc(k),key);
	else Delete(rc(k),key);
	return;
}

int Queryrank(int k,int num)
{
	if (k==0) return 0;
	if (v(k)==num) return s(lc(k))+1;
	else if (v(k)<num) return s(lc(k))+c(k)+Queryrank(rc(k),num);
	else return Queryrank(lc(k),num);
}

int Querynum(int k,int num)
{
	if (k==0) return 0;
	while (1){
		if (num<=s(lc(k))) k=lc(k);
		else if (num>s(lc(k))+c(k)) num-=s(lc(k))+c(k),k=rc(k);
		else return v(k);
	}
}

int Pre(int k,int num)
{
	if (k==0) return -2100000000;
	if (v(k)>=num) return Pre(lc(k),num);
	return max(v(k),Pre(rc(k),num));
}

int Aft(int k,int num)
{
	if (k==0) return 2100000000;
	if (v(k)<=num) return Aft(rc(k),num);
	return min(Aft(lc(k),num),v(k));
}

int main()
{
	freopen("testdata3369_2.in","r",stdin);
	freopen("testdata3369_2.out","w",stdout);
	scanf("%d",&n);
	root=tot=0;
	for (int I=1;I<=n;I++){
		int opt,num;
		scanf("%d%d",&opt,&num);
		if (opt==1) Insert(root,num);
		else if (opt==2) Delete(root,num);
		else if (opt==3) printf("%d\n",Queryrank(root,num));
		else if (opt==4) printf("%d\n",Querynum(root,num));
		else if (opt==5) printf("%d\n",Pre(root,num));
		else printf("%d\n",Aft(root,num));
	}	
	return 0;
}