#include<iostream>

#include<cstring>

#include<cstdio>

#include<algorithm>

using namespace std;

long long n,k,m,x,s,a[],b[],c[],d[];

int main()

{

    scanf("%I64d%I64d%I64d%I64d%I64d",&n,&m,&k,&x,&s);

    for(int i = ;i <= m;i++)   scanf("%I64d",&a[i]);

    for(int i = ;i <= m;i++)   scanf("%I64d",&b[i]);

    for(int i = ;i <= k;i++)   scanf("%I64d",&c[i]);

    for(int i = ;i <= k;i++)   scanf("%I64d",&d[i]);

    a[] = x;

    b[] = ;

    c[] = ;

    d[] = ;

    long long ans = n*x;

    for(int i = ;i <= m;i++)

    {

        if(s < b[i])    continue;

        int ss = s-b[i];

        int t = lower_bound(d,d+k+,ss)-d;

        int l = ,r = k+;

        while(l < r)

        {

            int mid = (l+r)/;

            if(d[mid] > ss) r = mid;

            else    l = mid+;

        }

        l--;

        long long tt = a[i]*(n-c[l]);

        ans = min(ans,tt);

    }

    printf("%I64d\n",ans);

    return ;

}