蜜汁RE......

#include<bits/stdc++.h>
using namespace std;
struct node
{
    node *ch[2];
    int r,v,s,w;
    node(int v):v(v){ch[0]=ch[1]=NULL;r=rand();s=w=1;}
    bool operator < (const node& rhs) const{return r<rhs.r;}
    int cmp(int x)const
    {
        if(x==v){return -1;}
        return x<v?0:1;
    }
    void maintain()
    {
        s=w;
        if(ch[0]!=NULL){s+=ch[0]->s;}
        if(ch[1]!=NULL){s+=ch[1]->s;}
    }
};
node *root;
int n,m;
void rotate(node* &o,int d)
{
    node* k=o->ch[d^1];o->ch[d^1]=k->ch[d];k->ch[d]=o;
    o->maintain();k->maintain();o=k;
}
void insert(node* &o,int x)
{
    if(o==NULL){o=new node(x);}
    else
    {
        int d=o->cmp(x);
        if(d==-1){o->w++;return;}
        insert(o->ch[d],x);
        if(o->ch[d]->r>o->r){rotate(o,d^1);}
    }
    o->maintain();
}
void remove(node* &o,int x)
{
    int d=o->cmp(x);
    if(d==-1)
    {
        if(o->w>1){o->w--;}
        else
        {
            node* u=o;
            if(o->ch[0]!=NULL&&o->ch[1]!=NULL)
            {
                int d2=(o->ch[0]->r>o->ch[1]->r?1:0);    
                rotate(o,d2);remove(o->ch[d2],x);
            }
            else if(o->ch[0]==NULL){o=o->ch[1];}else{o=o->ch[0];}
            delete u;    
        }
    }
    else{remove(o->ch[d],x);}
    if(o!=NULL){o->maintain();}
}
int rank(node* o,int x,int flag)
{
    int d=o->cmp(x);
    int s=(o->ch[0]==NULL?0:o->ch[0]->s);
    if(d==-1){if(!flag){return s+1;}else{return s+o->w;}}
    else if(!d){return rank(o->ch[0],x,flag);}
    else{return s+o->w+rank(o->ch[1],x,flag);}
}
int kth(node* o,int k)
{
    if(o==NULL||k<=0||k>o->s){return 0;}
    int s=(o->ch[0]==NULL?0:o->ch[0]->s);
    if(s+1<=k&&k<=s+o->w){return o->v;}
    else if(k<=s){return kth(o->ch[0],k);}
    else{return kth(o->ch[1],k-s-o->w);}
}
void removetree(node* &x)
{
    if(x->ch[0]!=NULL){removetree(x->ch[0]);}
    if(x->ch[1]!=NULL){removetree(x->ch[1]);}
    delete x;
    x=NULL;
}
int pre(node* o,int x){insert(o,x);int ans=kth(o,rank(o,x,0)-1);remove(o,x);return ans;}
int suc(node* o,int x){insert(o,x);int ans=kth(o,rank(o,x,1)+1);remove(o,x);return ans;}
int main()
{
    int i,j,x,flag,tmp;
    cin>>n;
    for(i=1;i<=n;i++)
    {
        scanf("%d%d",&flag,&x);
        if(flag==1){insert(root,x);}
        else if(flag==2){remove(root,x);}
        else if(flag==3){printf("%d\n",rank(root,x,0));}
        else if(flag==4){printf("%d\n",kth(root,x));}
        else if(flag==5){printf("%d\n",pre(root,x));}
        else{printf("%d\n",suc(root,x));}
    }
    removetree(root);
    return 0;
}