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#include <algorithm>
#include <cstdint>
#include <set>
#include <tuple>
#include <vector>

class Stock {
private:
    uint64_t cur_num = 0;
    std::vector<int> w_val;
    std::vector<int> v_val;

    struct Param {
        int param;
        uint64_t box_num;

        bool operator<(const Param& rhs) const {
            return std::tie(param, rhs.box_num) < std::tie(rhs.param, box_num);
        }
    };

    std::set<Param> w_set;
    std::set<Param> v_set;

    int get_box(int param, const std::set<Param>& cur_set) {
        auto it = std::lower_bound(cur_set.begin(), cur_set.end(), param,
                                   [](const Param& lhs, const int rhs) {return lhs.param < rhs;});

        if (it == cur_set.end()) {
            return -1;
        } else {
            uint64_t box_num = it->box_num;
            w_set.erase({w_val[box_num], box_num});
            v_set.erase({v_val[box_num], box_num});
            return box_num;
        }
    }

public:
    void add(int w, int v) {
        w_val.push_back(w);
        v_val.push_back(v);
        w_set.insert({w, cur_num});
        v_set.insert({v, cur_num});
        ++cur_num;
    }

    int get_by_w(int min_w) {
        return get_box(min_w, w_set);
    }

    int get_by_v(int min_v) {
        return get_box(min_v, v_set);
    }
};