// bzoj2006

#include<algorithm>

#include<iostream>

#include<cstdlib>

#include<cstring>

#include<cstdio>

#include<cmath>

#include<queue>

#define LL long long

#define inf 2147483640

#define Pi acos(-1.0)

#define free(a) freopen(a".in","r",stdin),freopen(a".out","w",stdout);

using namespace std;

inline int getint() {

	int x=0,f=1;char ch=getchar();

	while (ch>'9' || ch<'0') {if (ch=='-') f=-1;ch=getchar();}

	while (ch>='0' && ch<='9') {x=x*10+ch-'0';ch=getchar();}

	return x*f;

}

const int maxn=500010;

struct data {

	int l,r,m,i;LL w;

	friend bool operator < (const data &a,const data &b) {

		return a.w<b.w;

	}

};

priority_queue<data> q;

int ST[maxn][30],bin[30],a[maxn],Log[maxn];

LL s[maxn];

int n,K,L,R;

inline int mina(register int x,register int y) {

	return s[x]<s[y] ? x : y;

}

inline int query(register int l,register int r) {

	int k=Log[r-l+1];

	return mina(ST[l][k],ST[r-bin[k]+1][k]);

}

int main() {

	bin[0]=1;for (int i=1;i<=19;i++) bin[i]=bin[i-1]<<1;

	n=getint(),K=getint(),L=getint(),R=getint();

	for (int i=1;i<=n;i++) s[i]=getint(),s[i]+=s[i-1];

	for (int i=1;i<=n;i++) ST[i][0]=i;

	for (int i=2;i<=n;i++) Log[i]=Log[i>>1]+1;

	for (int j=1;j<=19;j++)

		for (int i=0;i+bin[j]<=n+1;i++)

			ST[i][j]=mina(ST[i][j-1],ST[i+bin[j-1]][j-1]);

	for (int i=L;i<=n;i++) {

		int l=max(i-R,0),r=i-L;

		int x=query(l,r);

		q.push((data){l,r,x,i,s[i]-s[x]});

	}

	LL ans=0;

	while (K--) {

		data t=q.top();ans+=t.w;q.pop();

		if (t.l<t.m) {

			int x=query(t.l,t.m-1);

			q.push((data){t.l,t.m-1,x,t.i,s[t.i]-s[x]});

		}

		if (t.m<t.r) {

			int x=query(t.m+1,t.r);

			q.push((data){t.m+1,t.r,x,t.i,s[t.i]-s[x]});

		}

	}

	printf("%lld",ans);

	return 0;

}