5 3 1
3 2 5 2 3

4

#include <bits/stdc++.h>
using namespace std;
typedef long long LL;
typedef double db;
LL n,k,T,a[100005],s[100005],qsum[100005],qpf[100005];
bool check(LL x){
    for(int i=1;i<=x;i++)   s[i]=a[i];
    sort(s+1,s+x+1);
    qsum[0]=0,qpf[0]=0;
    for(int i=1;i<=x;i++)   qsum[i]=qsum[i-1]+s[i];
    for(int i=1;i<=x;i++)   qpf[i]=qpf[i-1]+s[i]*s[i];
    db fc=0,avg=0;
    for(int i=1;i<=k;i++) avg+=(db)s[i]/k;
    fc=(qpf[k]-2*avg*qsum[k]+k*avg*avg)/k;
    if(T>=fc){
        return true;
    }
    for(int i=k+1;i<=x;i++){
        avg=avg-(db)s[i-k]/k+(db)s[i]/k;
        fc=(qpf[i]-qpf[i-k]-2*avg*(qsum[i]-qsum[i-k])+k*avg*avg)/k;
        if(T>=fc){
            return true;
        }
    }
    return false;
}

int main(){
    cin>>n>>k>>T;
    for(int i=1;i<=n;i++)   cin>>a[i];
    LL l=k,r=n;
    LL ans=n+1;
    while(l<=r){
        int mid=l+(r-l)/2;
        if(check(mid)){
            ans=mid;
            r=mid-1;
        }else{
            l=mid+1;
        }
    }
    if(ans>n) cout<<-1;
    else cout<<ans;
    return 0;
}