#include <iostream>
#include <string>
#include <vector>
#include <list>

using namespace std;

class HashTable {
    vector<list<int>> table;

    int hash_f(int value) {
        value *= value;
        value >>= 11;
        return value % 1024;
    }

public:
    HashTable() {
        table.resize(100000);
    }

    void add(int item) {
        int h = hash_f(item);
        table[h].push_front(item);
    }

    int find(int item) {
        int cur;
        list<int>::iterator p_begin;
        int h = hash_f(item);
        p_begin = table[h].begin();
        while (p_begin != table[h].end()) {
            cur = *p_begin;
            if (cur == item) {
                return 1;
            }
            advance(p_begin, 1);
        }
        return 0;

    }

    void del(int item) {
        int h = hash_f(item);
        table[h].remove(item);
    }
};

class Set {
    HashTable t;
public:
    void ad(int item) {
        if (!t.find(item)) {
            t.add(item);
        }
    }

    int exists(int item) {
        return t.find(item);
    }

    void dell(int item) {
        t.del(item);
    }

};


int main() {
    int k;
    string s1;
    Set s;
    freopen("set.in", "r", stdin);
    freopen("set.out", "w", stdout);
    while (cin >> s1) {
        if (s1 == "insert") {
            cin >> k;
            s.ad(k);
        } else if (s1 == "exists") {
            cin >> k;
            if (s.exists(k)) {
                cout << "true\n";
            } else {
                cout << "false\n";
            }
        } else if (s1 == "delete") {
            cin >> k;
            s.dell(k);
        }
    }


    return 0;
}