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)

///Bismillahir Rahmanir Rahim
#include<bits/stdc++.h>

#define                           int                         long long
#define                           fi                          first
#define                           si                          second
#define                           mp                          make_pair
#define                           pb                          push_back
#define                           pi                          pair<int,int>
#define                           clr(x)                      memset(x,0,sizeof(x));
#define                           f(i,l,r)                    for(int i=l;i<=r;i++)
#define                           rf(i,r,l)                   for(int i=r;i>=l;i--)
#define                           done(i)                     cout<<"done = "<<i<<endl;
#define                           fast                        ios_base::sync_with_stdio(false);cin.tie(0);cout.tie(0);




using namespace std;

const int inf=1e18;
const int mod=1e9+7;
const int M=100009;

inline int bigmod(int B,int P){int R=1;while(P>0){if(P&1){R=(R*B)%mod;}P>>=1;B=(B*B)%mod;}return R;}
inline int ad(int x,int y){int ret=(x%mod+y%mod)%mod;if(ret<0){ret+=mod,ret=ret%mod;}return ret;}
inline int sub(int x,int y){int ret=((x%mod)-(y%mod)+mod)%mod;if(ret<0){ret+=mod,ret=ret%mod;}return ret;}
inline int gun(int x,int y){int ret=((x%mod)*(y%mod))%mod;if(ret<0){ret+=mod,ret=ret%mod;}return ret;}

int n,m,v,p;
vector<pi>vec;
int a[M+3];
bool vis[M+3];
bool chk(int idx)
{
   int big=p-1;
   int use=v-1;
   int mn=min(big,use);
   big-=mn;
   use-=mn;
   vector<pi>yo;
   if(vis[idx])return true;
   int mx=vec[idx].fi+m;
   int sum=use*m;
   //cout<<sum<<" ### "<<endl;
   for(int i=p-1;i<n;i++)
   {
       if(i==idx)continue;
       int val=vec[i].fi;
       int gap=mx-val;
       if(gap<0)
       {
           //cout<<i<<" "<<mx<<" "<<val<<endl;
       }
       if(gap<0)return false;
       int can=min(gap,m);
       sum-=can;
   }
   if(sum<=0)return true;
   else return false;
}
 main()

{
    fast
    cin>>n>>m>>v>>p;
    f(i,1,n)
    {
        int x;
        cin>>x;
        a[i]=x;
        vec.pb(mp(x,i));
    }
    sort(vec.rbegin(),vec.rend());
    int last;
    for(int i=0;i<p;i++)
    {
        vis[i]=true;
        last=vec[i].fi;
    }
    for(int i=p;i<n;i++)
    {
        if(vec[i].fi==last)
        {
            vis[i]=true;
        }
    }
   // cout<<chk(3)<<"#"<<endl;
    int lo=0,hi=n-1;
    while(hi-lo>=2)
    {
        int mid=(lo+hi)>>1;
        if(chk(mid))lo=mid;
        else hi=mid-1;
    }
    int ses=0;
    for(int i=lo;i<=hi;i++)
    {
        if(chk(i))ses=i;
    }
    if(ses==0)
    {
        cout<<"0"<<endl;
        return 0;
    }
    ses=ses+1;
    cout<<ses<<endl;
    return 0;

}