Problem:
Score : 700 points

Problem Statement

N problems are proposed for an upcoming contest. Problem i has an initial integer score of A_i points.

M judges are about to vote for problems they like. Each judge will choose exactly V problems, independently from the other judges,
and increase the score of each chosen problem by 1.

After all M judges cast their vote, the problems will be sorted in non-increasing order of score, and the first P problems will be chosen for the problemset.
Problems with the same score can be ordered arbitrarily, this order is decided by the chief judge.

How many problems out of the given N have a chance to be chosen for the problemset?

Constraints

2 \le N \le 10^5

1 \le M \le 10^9

1 \le V \le N - 1

1 \le P \le N - 1

0 \le A_i \le 10^9

Input

Input is given from Standard Input in the following format:

N M V P
A_1 A_2 ... A_N

Output

Print the number of problems that have a chance to be chosen for the problemset.

Sample Input 1

6 1 2 2
2 1 1 3 0 2

Sample Output 1

5

If the only judge votes for problems 2 and 5, the scores will be 2 2 1 3 1 2.
The problemset will consist of problem 4 and one of problems 1, 2, or 6.

If the only judge votes for problems 3 and 4, the scores will be 2 1 2 4 0 2.
The problemset will consist of problem 4 and one of problems 1, 3, or 6.

Thus, problems 1, 2, 3, 4, and 6 have a chance to be chosen for the problemset. On the contrary, there is no way for problem 5 to be chosen.

Sample Input 2

6 1 5 2
2 1 1 3 0 2

Sample Output 2

3

Only problems 1, 4, and 6 have a chance to be chosen.

Sample Input 3

10 4 8 5
7 2 3 6 1 6 5 4 6 5

Sample Output 3

8

Solution in C++14 (GCC 5.4.1) (judge verdict: Wrong Answer)

#include <bits/stdc++.h>
#include <cmath>

const double PI = 3.14159265358979323846;
using namespace std;
typedef long long ll;
const double EPS = 1e-9;
//#define rep(i, n) for (int i = 0; i < (n); ++i)
#define rep(i, n) for (ll i = 0; i < (n); ++i)
//typedef pair<ll, ll> P;
typedef pair<ll, ll> P;
const ll INF = 10e17;
#define cmin(x, y) x = min(x, y)
#define cmax(x, y) x = max(x, y)
#define ret() return 0;

std::istream &operator>>(std::istream &in, set<int> &o) {
    ll a;
    in >> a;
    o.insert(a);
    return in;
}

std::istream &operator>>(std::istream &in, queue<int> &o) {
    ll a;
    in >> a;
    o.push(a);
    return in;
}

bool contain(set<int> &s, int a) { return s.find(a) != s.end(); }

//ofstream outfile("log.txt");
//outfile << setw(6) << setfill('0') << prefecture << setw(6) << setfill('0') << rank << endl;
// std::cout << std::bitset<8>(9);

//const ll mod = 1e10;
typedef priority_queue<ll, vector<ll>, greater<ll> > PQ_ASK;

#include <iostream>
#include <vector>

using namespace std;

bool can_choose(ll n, ll m, ll v, ll p, vector<ll> &problems, ll border) {
    // borderを当選させたい。可能か？
    if (border <= p) return true;
    ll target = problems[p];
    if (problems[border] + m < target) return false;

    ll budget = v * m;
    // border問目に全員が投票
    // P-1問目までは全員が投票
    // p問目からborder問目まではborder問目と一致するように投票
    // border+1問目移行は全部上げる
    // 票が余ったらfalse

    auto allocate = [&](ll ma) {
        ll k = min({budget, m, ma});
        budget -= k;
        return k;
    };

    ll border_point = problems[border] + allocate(INF);
    rep(i, p - 1) allocate(INF);

    for (ll i = border + 1; i < n; i++) allocate(INF);

    auto allocate_for_border_point = [&](ll i) {
        ll from = problems[i];
        assert(border_point >= from);
        ll diff = border_point - from;
        allocate(diff);
    };

    for (ll i = p; i < border; i++) allocate_for_border_point(i);

    return budget == 0;
}


int main() {
    ll n, m, v, p;
    cin >> n >> m >> v >> p;

    vector<ll> problems(n);
    rep(i, n) cin >> problems[i];
    sort(problems.rbegin(), problems.rend());

    int ans = 0;
    rep(i, n) if (can_choose(n, m, v, p, problems, i)) ans++;
    cout << ans << endl;

}