#include <bits/stdc++.h>
using namespace std;

inline void read(int& x)
{
	x = 0;
	int f = 1;
	
	char ch = getchar();
	while (ch < 48 || ch > 57)
	{
		if (ch == 45) f = -1;
		ch = getchar();
	}
	while (ch >= 48 && ch <= 57)
	{
		x = (x << 3) + (x << 1) + (ch ^ 48);
		ch = getchar();
	}
	
	x = x * f;
}

inline void write(int x)
{
	if (x < 0)
	{
		x = -x;
		putchar(45);
	}
	if (x > 9) write(x / 10);
	putchar(x % 10 + 48);
}

int a[100001], line;
double alpha = 7.5;

int val[100001];
int cnt[100001];
int size[100001];
int size_fact[100001];
int size_delet[100001];
int lc[100001];
int rc[100001];
int num;
int root;

inline void update_size(int o)
{
	size[o] = size[lc[o]] + size[rc[o]] + cnt[o];
	size_fact[o] = size_fact[lc[o]] + size_fact[rc[o]] + 1;
	size_delet[o] = size_delet[lc[o]] + size_delet[rc[o]] + (cnt[o] > 0);
}

inline void flatten(int o)
{
	if (!o) return;
	flatten(lc[o]);
	if (cnt[o]) a[++line] = o;
	flatten(rc[o]);
}

void build(int L, int R, int& o)
{
	int mid = (L + R) >> 1;
	o = a[mid];
	lc[o] = rc[o] = 0;
	
	if (L < mid) build(L, mid - 1, lc[o]);
	if (R > mid) build(mid + 1, R, rc[o]);
	
	update_size(o);
	return;
}

void rebuild(int& o)
{
	line = 0;
	flatten(o);
	build(1, line, o);
}

inline void judge(int& o)
{
	if(cnt[o] && (size_fact[o] * alpha <= (double)max(size_fact[lc[o]], size_fact[rc[o]]) ||
				  size_fact[o] * alpha >= (double)size_delet[o]))
	rebuild(o);
}

void insert(int& o, int x)
{
	if (!o)
	{
		o = ++num;
		val[o] = x;
		cnt[o] = 1;
		size[o] = size_fact[o] = size_delet[o] = 1;
		return;
	}
	
	if (val[o] == x)
		++cnt[o];
	else if (x < val[o])
		insert(lc[o], x);
	else if (x > val[o])
		insert(rc[o], x);
	
	update_size(o);
	judge(o);
	return;
}

void delet(int& o, int x)
{
	if (val[o] == x)
		--cnt[o];
	else if (x < val[o])
		delet(lc[o], x);
	else if (x > val[o])
		delet(rc[o], x);
	
	update_size(o);
	judge(o);
	return;
}

int query_rank(int o, int x)
{
	if (val[o] == x) return size[lc[o]] + 1;
	if (x < val[o]) return query_rank(lc[o], x);
	if (x > val[o]) return size[lc[o]] + cnt[o] + query_rank(rc[o], x);
}

int query_num(int o, int k)
{
	if (size[lc[o]] >= k) return query_num(lc[o], k);
	if (size[lc[o]] + cnt[o] < k) return query_num(rc[o], k - size[lc[o]] - cnt[o]);
	return val[o];
}

inline int query_pre(int x)
{
	int o = root;
	int res = -2147483647;
	while (o)
	{
		if (val[o] < x)
		{
			if (cnt[o]) res = val[o];
			o = rc[o];
		}
		else if (val[o] >= x) o = lc[o];
	}
	return res;
}

inline int query_sub(int x)
{
	int o = root;
	int res = 2147483647;
	while (o)
	{
		if (val[o] > x)
		{
			if (cnt[o]) res = val[o];
			o = lc[o];
		}
		else if (val[o] <= x) o = rc[o];
	}
	return res;
}

int n;

signed main(void)
{
	read(n);
	
	while (n--)
	{
		int op, x;
		read(op); read(x);
		
		switch(op)
		{
			case 1: insert(root, x); break;
			case 2: delet(root, x); break;
			case 3: write(query_rank(root, x)); putchar('\n'); break;
			case 4: write(query_num(root, x)); putchar('\n'); break;
			case 5: write(query_pre(x)); putchar('\n'); break;
			case 6: write(query_sub(x)); putchar('\n'); break;
		}
	}
	
	return 0;
}

考虑到了重复插入，所以开了三个 size 数组，一个用来存子节点个数，一个用来存数字个数，一个用来存不算删除过的点的节点个数。其他的，大概是没有问题了罢？求助