#include <bits/stdc++.h>
using namespace std;
int main(int argc, char const *argv[]) {
  ios::sync_with_stdio(false);
  long long n, m, k;
  cin >> n >> m >> k;
  long long x, s;
  cin >> x >> s;
  pair<long long, long long> a[m];
  for (int i = 0; i < m; i++) cin >> a[i].second;
  for (int i = 0; i < m; i++) cin >> a[i].first;
  sort(a, a + m);
  pair<long long, long long> c[k];
  for (int i = 0; i < k; i++) cin >> c[i].first;
  for (int i = 0; i < k; i++) cin >> c[i].second;
  long long mn[m];
  mn[0] = a[0].second;
  for (int i = 1; i < m; i++) {
    mn[i] = min(mn[i - 1], a[i].second);
  }
  long long ans = n * x;
  for (int i = 0; i < m; i++) {
    if (a[i].first <= s) ans = min(ans, n * a[i].second);
  }
  for (int i = 0; i < k; i++) {
    if (c[i].second > s) break;
    int t = c[i].first;
    int k =
        upper_bound(a, a + m,
                    pair<long long, long long>(s - c[i].second, 1LL << 60)) -
        a;
    k--;
    if (k >= 0) {
      ans = min(ans, (n - t) * min(x, mn[k]));
    }
    ans = min(ans, (n - t) * x);
  }
  ans = max(ans, 0LL);
  printf("%lld\n", ans);
  return 0;
}
