#include <iostream>
#include <bits/stdc++.h>
#include <fstream>
using namespace std;
ifstream f("hashuri.in");
ofstream g("hashuri.out");
set<int> s;
int main()
{
    int N, i, q, x;
    f>>N;
    for(i=0;i<N;i++)
    {
        f>>q>>x;
        if(q==1)
            s.insert(x);
        else if(q==2)
            s.erase(x);
        else
            g<<s.count(x)<<'\n';
    }
    return 0;
}