#pragma comment(linker, "/stack:200000000")
#pragma GCC optimize("Ofast")
#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,tune=native")

#include <bits/stdc++.h>
#include <cmath>
using namespace std;
const int maxen = 106033;
const int maxen2 = 60493;
const int inf = -2e9;
const int del = 2e9;


int hashf(int x) {

    return x % maxen;
}

bool exists (vector <int> &headPos,vector <int> &headNeg, int x) {

    if (x >= 0) {
        int pos = hashf(x);
        bool check = false;
        while (true) {
            if (headPos[pos] == inf) {
                break;
            }
            if (headPos[pos] == x) {
                check = true;
                break;
            }
            pos = (pos + 1) % maxen;
        }
        return check;
    } else {
        x = abs(x);
        int pos = hashf(x);
        bool check = false;
        while (true) {
            if (headNeg[pos] == inf) {
                break;
            }
            if (headNeg[pos] == x) {
                check = true;
                break;
            }
            pos = (pos + 1) % maxen;
        }
        return check;
    }

}
void add (vector <int> &headPos,vector <int> &headNeg, int x) {

    if (x >= 0) {
        if (exists(headPos, headNeg, x) == false) {
            int pos = hashf(x);
            while (true) {
                if (headPos[pos] == inf) {
                    headPos[pos] = x;
                    break;
                } else {
                    pos = (pos + 1) % maxen;
                }
            }

        }
    } else {

        if (exists(headPos, headNeg, x) == false) {
            x = abs(x);
            int pos = hashf(x);
            while (true) {
                if (headNeg[pos] == inf) {
                    headNeg[pos] = x;
                    break;
                } else {
                    pos = (pos + 1) % maxen;
                }
            }

        }
    }




}
void deletef(vector <int> &headPos,vector <int> &headNeg, int x) {

    if (x >= 0) {
        if (exists(headPos, headNeg, x) == true) {
            int pos = hashf(x);
            while (true) {
                if (headPos[pos] == x) {
                    headPos[pos] = del;
                    break;
                } else {
                    pos = (pos + 1) % maxen;
                }
            }
        }
    } else {
        if (exists(headPos, headNeg, x) == true) {
            x = abs(x);
            int pos = hashf(x);
            while (true) {
                if (headNeg[pos] == x) {
                    headNeg[pos] = del;
                    break;
                } else {
                    pos = (pos + 1) % maxen;
                }
            }
        }
    }

}
int main()
{

    freopen("set.in", "r", stdin);
    freopen("set.out", "w", stdout);
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);

    vector <int> headPos(maxen, inf);
    vector <int> headNeg(maxen, inf);
    string str;

    while (cin >> str) {
        if (str == "insert") {
            int x;
            cin >> x;
            add(headPos,headNeg, x);
        }
        if (str == "delete") {
            int x;
            cin >> x;
            deletef(headPos,headNeg, x);
        }
        if (str == "exists") {
            int x;
            cin >> x;
            if (exists(headPos,headNeg, x)) {
                cout << "true\n";
            } else {
                cout << "false\n";
            }

        }
    }




}