#include <iostream>
#include <climits>
#include <algorithm>
using namespace std;
#define MAXSIZE 200005
long long n,m,k,x,s,a[MAXSIZE],b[MAXSIZE],c[MAXSIZE],d[MAXSIZE],rm,rem,t,ans;
 
int main() {
	scanf("%lld %lld %lld", &n, &m, &k);scanf("%lld %lld",&x, &s);
	for(int i=1; i<=m; ++i) scanf("%lld", &a[i]);
	for(int i=1; i<=m; ++i) scanf("%lld", &b[i]);
	for(int i=1; i<=k; ++i) scanf("%lld", &c[i]);
	for(int i=1; i<=k; ++i) scanf("%lld", &d[i]);
	a[0]=x;b[0]=0;
	c[0]=0;d[0]=0;
	ans=n*x;
	for(int i=0; i<=m; ++i){
		if(b[i]>s)continue;
		int l=-1, r=k+1, mid;
		rem=s-b[i];
		// ans=min(ans, a[i]*n);
		// mid=(l+r)/2;
		while(l+1<r){
			mid=(l+r)/2;
			if(d[mid]<=rem)l=mid;
			else if(d[mid]>rem)r=mid;
			// mid=(l+r)/2;
		}
		ans=min(ans, a[i]*(n-c[l]));
	}
	printf("%lld\n", ans);
	return 0;
}

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OTQgMSAxCjI2IDMyNAo3CjIzNgo3Nwo1Cg==

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