#include <bits/stdc++.h>
using namespace std;
static const int maxn = 2e5 + 10;
struct proc {
  long long v, c;
} a[maxn], b[maxn];
int cmp(proc a, proc b) { return a.c < b.c; }
int main() {
  long long n, m, k, x, s;
  while (scanf("%lld %lld %lld", &n, &m, &k) != EOF) {
    scanf("%lld %lld", &x, &s);
    long long ans = n * x;
    a[0].v = x;
    a[0].c = 0;
    for (int i = 1; i <= m; i++) {
      scanf("%lld", &a[i].v);
    }
    for (int i = 1; i <= m; i++) {
      scanf("%lld", &a[i].c);
    }
    for (int i = 1; i <= k; i++) {
      scanf("%lld", &b[i].v);
    }
    for (int i = 1; i <= k; i++) {
      scanf("%lld", &b[i].c);
    }
    sort(a + 1, a + m + 1, cmp);
    for (int i = 0; i <= m; i++) {
      if (a[i].c > s) {
        break;
      }
      int rest = s - a[i].c;
      long long maxx = 0;
      int l = 1, r = k;
      while (l <= r) {
        int mid = (l + r) / 2;
        if (b[mid].c <= rest) {
          maxx = max(maxx, b[mid].v);
          l = mid + 1;
        } else {
          r = mid - 1;
        }
        if (n - maxx <= 0) {
          ans = 0;
        } else
          ans = min(ans, (long long)(n - maxx) * a[i].v);
      }
    }
    printf("%lld\n", ans);
  }
  return 0;
}
