#include <cstdio>
#include <cstring>
#include <iostream>
#include <algorithm>

using namespace std;
#define int long long
const int N = 1e5 + 5, INF = 2147483647;

int n;
struct node {
	int l, r;
	int key, val;
	int cnt, size;
} tr[N];

int root, idx;

void pushup(int p) {
	tr[p].size = tr[tr[p].l].size + tr[tr[p].r].size + tr[p].cnt;
}

int get_node(int key) {
	tr[++idx].key = key;
	tr[idx].val = rand();
	tr[idx].cnt = tr[idx].size = 1;
	return idx;
}

void zig(int &p) {
	int q = tr[p].l;
	tr[p].l = tr[q].r, tr[q].r = p, p = q;
	pushup(tr[p].r), pushup(p);
}

void zag(int &p) {
	int q = tr[p].r;
	tr[p].r = tr[q].l, tr[q].l = p, p = q;
	pushup(tr[p].l), pushup(p);
}

void build() {
	get_node(-INF), get_node(INF);
	root = 1, tr[1].r = 2;
	pushup(root);
	if(tr[1].val < tr[2].val) {
		zag(root);
	}
}

void insert(int &p, int key) {
	if(!p) {
		p = get_node(key);
	} else if(tr[p].key == key) {
		tr[p].cnt++;
	} else if(tr[p].key > key) {
		insert(tr[p].l, key);
		if(tr[tr[p].l].val > tr[p].val) {
			zig(p);
		}
	} else {
		insert(tr[p].r, key);
		if(tr[tr[p].r].val > tr[p].val) {
			zag(p);
		}
	}
	pushup(p);
}
 
int get_rank_by_key(int p, int key) {
	if(!p) {
		return 0;
	}
	if(tr[p].key == key) {
		return tr[tr[p].l].size + 1;
	}
	if(tr[p].key > key) {
		return get_rank_by_key(tr[p].l, key);
	}
	return tr[tr[p].l].size + tr[p].cnt + get_rank_by_key(tr[p].r, key);
}

int get_key_by_rank(int p, int rank) {
	if(!p) {
		return INF;
	}
	if(tr[tr[p].l].size >= rank) {
		return get_key_by_rank(tr[p].l, rank);
	}
	if(tr[tr[p].l].size + tr[p].cnt >= rank) {
		return tr[p].key;
	}
	return get_key_by_rank(tr[p].r, rank - tr[tr[p].l].size - tr[p].cnt);
}

int get_prev(int p, int key) {
	if(!p) {
		return -INF;
	}
	if(tr[p].key >= key) {
		return get_prev(tr[p].l, key);
	}
	return max(tr[p].key, get_prev(tr[p].r, key));
}

int get_next(int p, int key) {
	if(!p) {
		return INF;
	}
	if(tr[p].key <= key) {
		return get_next(tr[p].r, key);
	}
	return min(tr[p].key, get_next(tr[p].l, key));
}

signed main() {
	build();

	scanf("%lld", &n);
	while(n--) {
		int op, x;
		scanf("%lld%lld", &op, &x);
		
		if (op == 5) {
			insert(root, x);
		} else if (op == 1) {
			printf("%lld\n", get_rank_by_key(root, x));
		} else if (op == 2) {
			printf("%lld\n", get_key_by_rank(root, x + 1));
		} else if (op == 3) {
			printf("%lld\n", get_prev(root, x));
		} else {
			printf("%lld\n", get_next(root, x));
		}
	}
		
	return 0;
}

这份代码样例输出

3
3
1
5

但是过了