9:1

#include<bits/stdc++.h>
#define optimize() ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
using namespace std;
int main()
{
    optimize();
    int q;
    cin>>q;
    set<int>s;
    while(q--)
    {
        int x,y;
        cin>>x>>y;
        if(x==1)
        {
           s.insert(y);
        }
        else if(x==2)
        {
            s.erase(y);
        }
        else if(x==3)
        {
            if(s.count(y)) cout<<"Yes\n";
            else cout<<"No\n";
        }
    }
}