先记个板子
#include<bits/stdc++.h>
using namespace std;
const int N = 1e5+5;
int n;
int rt,son[N][2],sz[N],va[N],pri[N],tot;
struct FHQ
{void pushup(int x) {sz[x]=sz[son[x][0]]+sz[son[x][1]]+1;}int merge(int x,int y){if(!x||!y) return x|y;if(pri[x]<pri[y]) return son[x][1]=merge(son[x][1],y),pushup(x),x;else return son[y][0]=merge(x,son[y][0]),pushup(y),y;}void split(int rt,int k,int &x,int &y){if(!rt) return x=y=0,void (0);if(va[rt]<=k) x=rt,split(son[rt][1],k,son[rt][1],y);else y=rt,split(son[rt][0],k,x,son[rt][0]);pushup(rt);}int kth(int rt,int k){if(k<=sz[son[rt][0]])return kth(son[rt][0],k);if(k==sz[son[rt][0]]+1)return rt;return kth(son[rt][1],k-sz[son[rt][0]]-1);}int nw(int k) {va[++tot]=k; sz[tot]=1; pri[tot]=rand(); return tot;}void ins(int k){int x,y;split(rt,k,x,y); rt=merge(merge(x,nw(k)),y);}void del(int k){int x,y,z;split(rt,k,x,y); split(x,k-1,x,z);z=merge(son[z][0],son[z][1]);rt=merge(merge(x,z),y);}int rk(int k){int x,y,res; split(rt,k-1,x,y); res=sz[x]+1;return rt=merge(x,y),res;}int pre(int k){int x,y,res; split(rt,k-1,x,y);int kk=kth(x,sz[x]);res=va[kk];return rt=merge(x,y),res;}int nxt(int k){int x,y,res; split(rt,k,x,y); res=va[kth(y,1)];return rt=merge(x,y),res;}
} tp;int main()
{scanf("%d",&n);while(n--){int c,x; scanf("%d%d",&c,&x);if(c==1) tp.ins(x);if(c==2) tp.del(x);if(c==3) printf("%d\n",tp.rk(x));if(c==4) printf("%d\n",va[tp.kth(rt,x)]);if(c==5) printf("%d\n",tp.pre(x));if(c==6) printf("%d\n",tp.nxt(x));}return 0;
}
