#include <bits/stdc++.h>
#include <ext/pb_ds/tree_policy.hpp>
#include <ext/pb_ds/assoc_container.hpp>
using namespace __gnu_pbds;
using namespace std;
struct Tree{
	int inf=1e9,idx=0;
	struct node{
		int x,tim;
		bool operator <(node o) const{
			if(x != o.x) return x < o.x;
			else return tim < o.tim;
		}
	};
	tree<node, null_type, less<node>,rb_tree_tag,tree_order_statistics_node_update> T;
	void insert(int x){T.insert({x,++idx});}
	bool have(int x){
		node cur={x,0};
		int order=T.order_of_key(cur);
		if(order+1>(int)T.size()) return 0;
		auto it=T.find_by_order(order);
		if((*it).x!=x) return 0;
		return 1;
	}
	void erase(int x){
		if(!have(x))return;
		node cur={x,0};
		int order=T.order_of_key(cur);
		auto it=T.find_by_order(order);
		T.erase(it);
	}
	int getrank(int x){return T.order_of_key({x,0})+1;}
	int getbyrank(int rank){
		if((int)T.size()<rank)return -inf;
		return (*T.find_by_order(rank-1)).x;
	}
	int getpre(int x){
		int rank=getrank(x);
		if(rank==1)return -inf;
		return getbyrank(rank-1);
	}
	int getnex(int x){
		int rank=getrank(x+1);
		if(rank>(int)T.size())return -inf;
		return getbyrank(rank);
	}
}tr;
int n,op,x;
signed main()
{
#ifdef ONLINE_JUDGE
	oj=0;
#endif
	cin>>n;
	while(n--){
		cin>>op>>x;
		switch(op){
			case 1:
				tr.insert(x);
				break;
			case 2:
				tr.erase(x);
				break;
			case 3:
				cout<<tr.getrank(x)<<endl;
				break;
			case 4:
				cout<<tr.getbyrank(x)<<endl;
				break;
			case 5:
				cout<<tr.getpre(x)<<endl;
				break;
			default:
				cout<<tr.getnex(x)<<endl;
		}
	}
	return 0;
}

(用的是pbds)