#include <bits/stdc++.h>
using namespace std;
map<int,bool>f;
int n,a;
char m;
int main()
{
    scanf("%d",&n);
    for(;n--;)
    {
        scanf("\n%c%d",&m,&a);
        if(m=='I')f[a]=true;
        else if(f[a])printf("Yes\n");
        else printf("No\n");
    }
    return 0;
}