Code：

#include<bits/stdc++.h>

#define endl '\n';
#define int long long

using namespace std;

const int N = 1e5 + 5;

int n;

struct Node{
  int ls, rs;
  int val, key;
  int size;
}tree[N];

int tot, root;

inline int newnode(int val){
  tot++;
  tree[tot].val = val;
  tree[tot].ls = 0;
  tree[tot].rs = 0;
  tree[tot].key = rand();
  tree[tot].size = 1;
  return tot;
}

inline void update(int node){
  tree[node].size = tree[tree[node].ls].size + tree[tree[node].rs].size;
}

void split(int node, int val, int &r1, int &r2){
  if(!node){
    r1 = 0;
    r2 = 0;
    return ;
  }
  if(tree[node].val <= val){
    r1 = node;
    split(tree[node].rs, val, tree[node].rs, r2);
  }
  else{
    r2 = node;
    split(tree[node].ls, val, r1, tree[node].ls);
  }
  update(node);
}

int merge(int x, int y){
  if(!x || !y){
    return x + y;
  }
  if(tree[x].key > tree[y].key){
    tree[x].rs = merge(tree[x].rs, y);
    update(x);
    return x;
  }
  else{
    tree[y].ls = merge(x, tree[y].ls);
    update(y);
    return y;
  }
}

int t1, t2, t3;

inline void insert(int val){
  split(root, val, t1, t2);
  root = merge(merge(t1, newnode(val)), t2);
}

inline void _delete(int val){
  split(root, val, t1, t3);
  split(t1, val - 1, t1, t2);
  t2 = merge(tree[t2].ls, tree[t2].rs);
  root = merge(merge(t1, t2), t3);
}

inline int _rank(int val){
  split(root, val - 1, t1, t2);
  int ans = tree[t1].size + 1;
  root = merge(t1, t2);
  return ans;
}

inline int query(int rank){
  int node = root;
  while(node){
    if(tree[tree[node].ls].size + 1 == rank){
      break;
    }
    else if(tree[tree[node].ls].size >= rank){
      node = tree[node].ls;
    }
    else{
      rank -= tree[tree[node].ls].size + 1;
      node = tree[node].rs;
    }
  }
  return tree[node].val;
}

inline int pre(int val){
  split(root, val - 1, t1, t2);
  int node = t1;
  while(tree[node].rs){
    node = tree[node].rs;
  }
  int ans = tree[node].val;
  root = merge(t1, t2);
  return ans;
}

inline int nxt(int val){
  split(root, val, t1, t2);
  int node = t2;
  while(tree[node].ls){
    node = tree[node].ls;
  }
  int ans = tree[node].val;
  root = merge(t1, t2);
  return ans;
}

void Solve(){
  srand(time(0));
  cin >> n;
  while(n--){
    int op;
    cin >> op;
    if(op == 1){
      int x;
      cin >> x;
      insert(x);
    }
    else if(op == 2){
      int x;
      cin >> x;
      _delete(x);
    }
    else if(op == 3){
      int x;
      cin >> x;
      cout << _rank(x) << '\n';
    }
    else if(op == 4){
      int x;
      cin >> x;
      cout << query(x) << '\n';
    }
    else if(op == 5){
      int x;
      cin >> x;
      cout << pre(x) << '\n';
    }
    else{
      int x;
      cin >> x;
      cout << nxt(x) << '\n';
    }
  }
}

signed main(){
  Solve();
  return 0;
}