#include<bits/stdc++.h>
using namespace std;
constexpr int M=1e5+5;
int n,m,x,s[M],p[M],t[M];
int read(){
	int x=0,f=1;char ch=getchar();
	while (!isdigit(ch)) {if (ch=='-') f=-1;ch=getchar();}
	while (isdigit(ch)) x=x*10+ch-48,ch=getchar();
	return x*f;
}
bool check(int s){
	int need=(x-1)/s+1;
	for (int i=0,lst;need>0&&i<=m;lst=t[i++])
		if (need<=p[i]-lst)
			need-=t[i+1]-t[i]; 
	return need<=0;
}
int main(){
	n=read();m=read();x=read();p[0]=read();
	for (int i=1;i<=n;i++) s[i]=read();
	sort(s+1,s+n+1); t[m+1]=0x3f3f3f3f;
	for (int i=1;i<=m;i++) t[i]=read();
	for (int i=1;i<=m;i++) p[i]=read();
	int l=1,r=n,ans=0;
	while (l<=r){
		int mid=l+r>>1;
		if (check(s[mid])) ans=n-mid+1,r=mid-1;
		else l=mid+1;
	}
	printf("%d\n",ans);
	return 0;
}