#include<iostream>
#include<string>

using namespace std;

long long getRand() {
    return (rand() << 15) + rand();
}

struct Node {
    long long key, pr;
    Node *left, *right;
    Node(int k) : key(k), pr(getRand()), left(NULL), right(NULL) {}
};

Node *root;

bool search(Node *tree, int key) {
    if (!tree) return false;
    if (tree->key == key) return true;
    if (tree->key < key) return search(tree->right, key);
    return search(tree->left, key);
}

pair < Node*, Node* > split(Node *tree, int k) {
    if(!tree) return make_pair((Node*)0, (Node*)0);
    if(tree->key <= k) {
        pair < Node*, Node* > p = split(tree->right, k);
        tree->right = p.first;
        return make_pair(tree, p.second);
    } else {
        pair < Node*, Node* > p = split(tree->left, k);
        tree->left = p.second;
        return make_pair(p.first, tree);
    }
}

Node* merge(Node* L, Node* R) {
    if(!L) return R;
    if(!R) return L;
    if(L->pr <= R->pr) {
        L->right = merge(L->right, R);
        return L;
    } else {
        R->left = merge(L, R->left);
        return R;
    }
}

Node* insert(Node* tree, int k) {
    Node* newnode = new Node(k);
    pair < Node*, Node* > p = split(tree, k);
    return merge(merge(p.first, newnode), p.second);
}

void delete_tree(Node* tree) {
    if(!tree) return;
    delete_tree(tree->left);
    delete_tree(tree->right);
    delete(tree);
}

Node* erase(Node* tree, int k) {
    pair < Node*, Node* > p = split(tree, k);
    pair < Node*, Node* > p2 = split(tree, k);
    delete_tree(p2.second);
    return merge(p2.first, p.second);
}

int main() {
    ios_base::sync_with_stdio(0);
    cin.tie(0); cout.tie(0);
    string s;
    while(cin >> s) {
        int k;
        cin >> k;
        if(s == "insert") {
            root = insert(root, k);
        }
        if(s == "delete") {
            root = erase(root, k);
        }
        if(s == "exists") {
            bool f = search(root, k);
            if(f) cout << "true" << endl;
            else cout << "false" << endl;
        }
    }
}