/**
 * Prof.Nicola
**/
#include <bits/stdc++.h>

using namespace std;
#define endl "\n"
#define mp make_pair
#define F first
#define S second
#define REP(i,l,r) for(long long i=(l);i<(r);i++)
#define PER(i,l,r) for(long long i=(r)-1;i>=(l);i--)
const long dx[4]={1,0,-1,0},dz[4]={0,1,0,-1};
const long double pi=3.14159265359;
const long long mod=1e9+7;
template<class T>void re(T&x){cin>>x;}
template<class T1,class T2> void re(pair<T1,T2>&x){re(x.first);re(x.second);}
template<class T>void re(vector<T>&x){for(long i=0;i<x.size();i++){re(x[i]);}}
template<class T>void re(deque<T>&x){for(long i=0;i<x.size();i++){re(x[i]);}}
template<class T>void out(T x){cout<<x<<" ";}
template<class T1,class T2>void out(pair<T1,T2>x){out(x.first);out(x.second);cout<<endl;}
template<class T>void out(vector<T>x,long l=0,long r=0){if(!r){r=x.size();}for(long i=l;i<r;i++){out(x[i]);}cout<<endl;}
template<class T>void out(deque<T>x,long l=0,long r=0){if(!r){r=x.size();}for(long i=l;i<r;i++){out(x[i]);}cout<<endl;}
template<class T>T cross(complex<T>x,complex<T>z){return (conj(x)*z).imag();}
template<class T>T dot(complex<T>x,complex<T>z){return (conj(x)*z).real();}
int main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    long long n,r,w,k,sum,ans=1e18;
    long double mx,slope;
    cin>>n>>r>>w>>k;
    r--;
    w--;
    vector<long long>v(n),cost(n),ok;
    re(v);
    v[r]+=k;
    mx=-1e18;
    REP(i,r+1,n){
        slope=((double)v[i]-v[r])/(i-r);
        if(slope>=mx){
            ok.push_back(i);
        }
        mx=max(mx,slope);
    }
    mx=-1e18;
    PER(i,0,r){
        slope=((double)v[i]-v[r])/(r-i);
        if(slope>=mx){
            ok.push_back(i);
        }
        mx=max(mx,slope);
    }
    sum=0;
    cost[w]=0;
    REP(i,w+1,n){
        sum+=max(0ll,v[i]-v[i-1]);
        cost[i]=sum;
    }
    sum=0;
    PER(i,0,w){
        sum+=max(0ll,v[i]-v[i+1]);
        cost[i]=sum;
    }
    REP(i,0,ok.size()){
        ans=min(ans,cost[ok[i]]);
    }
    cout<<ans<<endl;
    return 0;
}