#include <bits/stdc++.h>
using namespace std;
const int P = 1e9 + 7, INF = 0x3f3f3f3f;
long long gcd(long long a, long long b) { return b ? gcd(b, a % b) : a; }
long long qpow(long long a, long long n) {
  long long r = 1 % P;
  for (a %= P; n; a = a * a % P, n >>= 1)
    if (n & 1) r = r * a % P;
  return r;
}
long long inv(long long first) {
  return first <= 1 ? 1 : inv(P % first) * (P - P / first) % P;
}
inline int rd() {
  int first = 0;
  char p = getchar();
  while (p < '0' || p > '9') p = getchar();
  while (p >= '0' && p <= '9') first = first * 10 + p - '0', p = getchar();
  return first;
}
const int N = 1e6 + 10;
int n, m, k, first, s;
struct _ {
  int a, b;
} a[N], b[N];
long long ans = ~0ull >> 1;
int chk(long long e) {
  if (e >= ans) return 1;
  int now = 0;
  for (int i = 1; i <= m; ++i) {
    while (now < k && (long long)a[i].b + b[now + 1].b <= s) ++now;
    if ((long long)a[i].b + b[now].b > s) continue;
    if (b[now].a >= n) return 1;
    if ((long long)(n - b[now].a) * a[i].a <= e) return 1;
  }
  return 0;
}
void ccc(long long first) {
  printf("chk(%lld)=%d\n", first, chk(first)), exit(0);
}
int main() {
  scanf("%d%d%d%d%d", &n, &m, &k, &first, &s);
  ans = min(ans, (long long)n * first);
  for (int i = 1; i <= m; ++i) scanf("%d", &a[i].a);
  for (int i = 1; i <= m; ++i) scanf("%d", &a[i].b);
  for (int i = 1; i <= k; ++i) scanf("%d", &b[i].a);
  for (int i = 1; i <= k; ++i) scanf("%d", &b[i].b);
  sort(a + 1, a + 1 + m, [](_ a, _ b) { return a.b > b.b; });
  for (int i = 1; i <= m; ++i)
    if (a[i].b <= s) ans = min(ans, (long long)n * a[i].a);
  for (int i = 1; i <= k; ++i)
    if (b[i].b <= s) {
      if (b[i].a >= n)
        ans = 0;
      else
        ans = min(ans, (long long)(n - b[i].a) * first);
    }
  long long l = 0, r = ans;
  while (l <= r) {
    if (chk(((l + r) >> 1)))
      ans = ((l + r) >> 1), r = ((l + r) >> 1) - 1;
    else
      l = ((l + r) >> 1) + 1;
  }
  printf("%lld\n", ans);
}
