#pragma once
#include <set>

namespace red_black {
namespace set {
using Key = int;

struct Tree {
    std::set<Key> s;

    void insert(Key x) {
        s.insert(x);
    }

    bool remove(Key x) {
        return s.erase(x);
    }

    bool find(Key x) {
        return s.contains(x);
    }

    size_t size() const {
        return s.size();
    }
};
}
}