本蒟蒻刚学STL，不懂为啥超时，实现两秒，其中 $1\leq n\leq 1000000$

#include<bits/stdc++.h>
#define Code using
#define by namespace
#define wjb std
Code by wjb;
int n,num;
char c;
set<int>s;
int main()
{
	cin>>n;
	while(n--&&cin>>c)
		if(c=='a')cin>>num,s.insert(num);
		else if(c=='d')cin>>num,s.erase(num);
		else cout<<*s.begin()<<"\n",s.erase(*s.begin());
	return 0;
}