https://cn.vjudge.net/contest/158362#problem/A
對前一半後一半分別維護一個set，操作時做相應調整即可

#include<stdio.h>
#include<set>
#include<queue>
using namespace std;

int n,type,aim,q;
queue<int> Q;
set<int> S1,S2;
set<int>::iterator it;

inline void mt()
{
    if (n && S1.size()!=(n>>1
 
))
    {
        if ((n>>1)<S1.size())
        {   
            it=S1.end();
            it--;
            S2.insert(*it);
            S1.erase(it);
        }
        else
        {
            S1.insert(*S2.begin());
            S2.erase(S2.begin());
        }
    }
}

int main()
{
    scanf
 
("%d",&q);
    for (;q--;)
    {
        scanf("%d",&type);
        if (type==1)
        {
            scanf("%d",&aim);
            Q.push(aim);
            n++;
            if (aim<*S2.begin()) S1.insert(aim);
            else S2.insert(aim);
            mt();
        }
        if (type==2
 
)
        {
            aim=Q.front();Q.pop();n--;
            if (aim<*S2.begin()) S1.erase(aim);
            else S2.erase(aim);
            mt();
        }
        if (type==3) printf("%d\n",*S2.begin());
    }
}