#include <bits/stdc++.h>
using namespace std;
signed main() {
  long long n, m, k;
  cin >> n >> m >> k;
  long long x, s;
  cin >> x >> s;
  long long ans = n * x;
  vector<pair<long long, long long>> a(m), b(k + 1);
  for (long long i = 0; i < m; i++) {
    cin >> a[i].second;
  }
  for (long long i = 0; i < m; i++) {
    cin >> a[i].first;
  }
  for (long long i = 0; i < k; i++) {
    cin >> b[i + 1].second;
  }
  for (long long i = 0; i < k; i++) {
    cin >> b[i + 1].first;
  }
  sort(a.begin(), a.end());
  sort(b.begin(), b.end());
  long long r = k;
  for (long long i = 0; i < m; i++) {
    while (r > 0 && b[r].first + a[i].first > s) {
      r--;
    }
    if (b[r].first + a[i].first <= s) {
      ans = min(ans, (n - b[r].second) * (a[i].second));
    }
  }
  for (long long i = 0; i < m; i++) {
    if (a[i].first > s) continue;
    ans = min(ans, (a[i].second) * n);
  }
  for (long long i = 1; i <= k; i++) {
    if (b[i].first > s) continue;
    ans = min(ans, (n - b[i].second) * x);
  }
  cout << ans;
}
