#include <iostream>
#include <algorithm>
using namespace std;
struct first
{
    long long time;
    long long cost;
} ;
bool cmp(first one, first sec)
{
    return one.time>sec.time;
}
int main()
{
    long long x,m,s,n,m1,minn,min2=2*1000000000,minnn=2*1000000000,i,k,q,qq;
    cin >> n >> m >> m1;
    cin >> x >> s;long long b[m1],b1[m1]; int f=2;first a[m];
    for (i=0;i<m;i++)
        cin >> a[i].time;
    for (i=0;i<m;i++)
       {
          cin >> a[i].cost;
          if ((a[i].time<min2) && (a[i].cost<=s))
          { f=3;min2=a[i].time;}
       }
    sort(a,a+m,cmp);
    for (i=0;i<m1;i++)
        cin >> b[i];
    for (i=0;i<m1;i++)
       {
           cin >> b1[i];if (b1[i]>s) continue;
         /*  minn=2*1000000000;f=0;
           for (q=0;q<m;q++)
            if ((a[q]<minn) && (a1[q]<=(s-b1[i])) )
           {
               minn=a[q];qq=(n-b[i])*a[q];f=1;
              // cout << minn << " " << a[q] << " " << b[i] << " " << qq << endl;
           }
           if (f==0) qq=((n-b[i])*x);
           if (qq<minnn) minnn=qq; */
           f=0;q=0;
          // while ((a[q].cost<(s-b1[i]) && (f==0)))
           while((f==0) || (q<m))
           {
               if (a[q].cost<(s-b1[i]))
                   {

               minn=a[q].time;qq=(n-b[i])*a[q].time;f=1;
                   }
                  // cout << minn << " " << a[q].time << " " << b[i] << " " << qq << endl;
               q++;
               if (qq<minnn) minnn=qq;
           }
           if (q==0) qq=((n-b[i])*x);

       }
    if (f==3) minnn=min2*n;
    if (f==2) minnn=x*n;
    cout << minnn;
}