Странные яблоки

#include <iostream>
#include <vector>
#include <algorithm>

using namespace std;

struct apple {
    unsigned num;
    unsigned down, up;

    apple(unsigned n = 0, unsigned d = 0, unsigned u = 0) : num(n), down(d), up(u) {}
};

int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);

    unsigned n;
    int s;
    cin >> n >> s;
    vector<apple> plus, minus;
    {
        unsigned a, b;
        apple c;
        for (unsigned i = 0; i < n; ++i) {
            cin >> a >> b;
            c = apple(i + 1, a, b);
            b < a ? minus.push_back(c) : plus.push_back(c);
        }
    }

    sort(plus.begin(), plus.end(),
            [](apple x, apple y) { return x.down < y.down; });
    sort(minus.begin(), minus.end(),
            [](apple x, apple y) { return x.up > y.up; });

    bool flag = true;
    for (unsigned i = 0; i < plus.size(); ++i) {
        s -= plus[i].down;
        if (s <= 0) { flag = false; }
        s += plus[i].up;
    }
    for (unsigned i = 0; i < minus.size(); ++i) {
        s -= minus[i].down;
        if (s <= 0) { flag = false; }
        s += minus[i].up;
    }
    if (flag) {
        for (unsigned i = 0; i < plus.size(); ++i) {
            cout << plus[i].num << " ";
        }
        for (unsigned i = 0; i < minus.size(); ++i) {
            cout << minus[i].num << " ";
        }
    } else {
        cout << -1;
    }
    cout << endl;
}