#include<bits/stdc++.h>
using namespace std;
 
template <class T1, class T2>
ostream& operator << (ostream& out, const pair <T1, T2> p)
{
        out << '(' << p.first << ',' << p.second << ')';
            return out;
}
 
template <class T1, class T2>
istream& operator >> (istream& in, pair<T1, T2> &p)
{
        in >> p.first >> p.second;
            return in;
}
 
template <class T>
istream& operator >> (istream& in, vector<T> &v)
{
        for (T &x : v)
                    in >> x;
            return in;
}
 
template <class T>
ostream& operator << (ostream& out, const vector<vector<T> > &v)
{
        for (const vector<T> &x : v)
                    out << x << '\n';
            return out;
}
 
template <class T>
ostream& operator << (ostream& out, const vector<T> &v)
{
        for (const T &x : v)
                    out << x << ' ';
            return out;
}

template <class T>
ostream& operator << (ostream& out,const set<T> &s)
{
        for (const T &x : s)
                out << x << ' ';
            return out;
}
 
 
#define ll long long
#define lf long double
#define pb push_back
#define mp make_pair
#define F first
#define S second
typedef pair <ll,ll > ii;
typedef vector <ll> vi;
typedef vector <ii> vii;
typedef vector <bool> vb;
typedef vector <vector <ll> > vv;
typedef vector <vector <vector<ll> > > vvv;
typedef vector <string> vs;
typedef vector <lf> vf;
#define sz(x) (ll)(x).size()
#define tr1(x) cerr << #x << ": " << x << nl
#define tr2(x, y) cerr << #x << ": " << x << " | " << #y << ": " << y << nl
#define tr3(x,y,z) cerr<<#x<<": "<<x<<" | "<<#y<<": "<<y<<" | "<<#z<<": "<<z<<nl
#define tr4(x,y,z,w) cerr<<#x<<": "<<x<<" | "<<#y<<": "<<y<<" | "<<#z<<": "<<z<<" | "<<#w<<": "<<w<<nl
#define trv(a) cerr<<#a<<": ";for(ll zz=0;zz<sz(a);zz++) cerr<<a[zz]<<" ";cerr<<nl
#define trset(s) cerr<<#s<<": ";for(auto &i:s) cerr<<i<<" ";cerr<<nl
#define epsilon 0.00000001L
#define inf 9999999999999999ll// ~ 10^16
#define nl endl
#define all(x) x.begin(), x.end()
#define r_all(x) x.rbegin(), x.rend()
#define fast()  ios_base::sync_with_stdio(false);cin.tie(NULL)
#define mod 1000000007ll
#define modulo 998244353ll
ll power(ll a,ll b){return b?power(a*a%mod,b/2)*(b%2?a:1)%mod:1;}


ll n,m,v,p;
vi a;


bool possible(ll ind)
{
    ll v1=v;
    v--;
    vi temp=a;
    a[ind]+=m;

    ll index=ind;
    for(ll i=0;i<n && v>0;i++)
    {
        if(temp[i]<=temp[ind])
        {
            if(i!=index)
            {
                a[i]+=m;
                v--;
            }
        }
        else
        {
            index=i;
            break;
        }
    }
    
    ll votes=v*m;
    if(votes>0)
    {
        for(ll i=0;i<n && votes>0;i++)
        {
            if(a[i]>a[ind])
            {
                votes-=m;
                a[i]+=m;
            }
        }
    }
    if(votes>0)
    {
        for(ll i=index;i<n && votes>0;i++)
        {
            if(a[i]<a[ind])
            {
                votes-=a[ind]-a[i];
                a[i]=a[ind];
            }
        }
    }
    if(votes>0)
    {
        for(ll i=n-1;i>=index && votes>0;i--)
        {
            if(a[i]==a[ind] )
            {
                ll ma=temp[i]+m;
                votes-=(ma-a[i]);
                a[i]=ma;
            }
        }
    }
    
    ll greater=0;
    for(ll i=0;i<n;i++)
    {
        if(a[i]>a[ind])
            greater++;
    }
    v=v1;
    a=temp;
    return greater<p;
}
int main()
{
    fast();
    cin>>n>>m>>v>>p;
    
    a.resize(n);
    cin>>a;
    
    sort(all(a));
    ll low=0;
    ll high=n-1;
    //possible(1);
    while(low<high)
    {
        ll mid=(low+high)/2;
        if(possible(mid))
            high=mid;
        else
            low=mid+1;
    }
    cout<<n-low<<nl;
}


Measured memory_bytes: 4760