Дрва со гумени бомбони

#include <iostream>
#include <algorithm>
using namespace std;
#define int long long

int arr[100005], pref[100005];

signed main() {
    #ifdef ONLINE_JUDGE
    ios::sync_with_stdio(0);
    cin.tie(0); cout.tie(0);
    #endif

    int n, p, d, l = 1, r, m, k = -1;
    cin >> n >> p >> d;
    r = d;
    for (int i = 0; i < n; i++) cin >> arr[i];
    sort(arr, arr + n);
    reverse(arr, arr + n);
    for (int i = 0; i < n; i++) {
        pref[i + 1] = pref[i] + arr[i];
        // cerr << "pref[" << i + 1 << "] = " << pref[i + 1] << '\n';
    }
    auto f = [&](int x) { ++x; return pref[min(x, n)] * (d / x) + pref[min(d % x, n)]; };
    while (l <= r) {
        m = (l + r) / 2;
        // cerr << "m = " << m << "\nf(m) = " << f(m) << endl;
        if (f(m) < p) {
            // mnogu malce
            // cerr << "mnogu malce\n";
            r = m - 1;
        }
        else {
            // cerr << "dovolno\n";
            // dovolno
            if (m == d && f(d + 1) >= p) {
                // se edno
                cout << "seedno";
                return 0;
            }
            l = m + 1;
            k = m;
        }
    }
    cout << k;
    return 0;
}