#include <bits/stdc++.h>
using namespace std;
vector<pair<long long int, long long int>> c;
pair<long long int, long long int> d[200003];
int main() {
  ios::sync_with_stdio(false);
  long long int n, m, k;
  cin >> n >> m >> k;
  long long int x, s;
  cin >> x >> s;
  c.resize(m);
  for (int i = 0; i < m; i++) {
    cin >> c[i].second;
  }
  for (int i = 0; i < m; i++) {
    cin >> c[i].first;
  }
  c.push_back(make_pair(0, x));
  sort(c.begin(), c.end());
  d[0].first = 0;
  d[0].second = 0;
  for (int i = 1; i <= k; i++) {
    cin >> d[i].second;
  }
  for (int i = 1; i <= k; i++) {
    cin >> d[i].first;
  }
  int start = 0, end = k;
  long long int ans = n * x;
  while (start <= m) {
    while (c[start].first + d[end].first > s) {
      if (end == 0) {
        cout << ans << endl;
        return 0;
      }
      end--;
    }
    long long int t = max(0LL, n - d[end].second);
    ans = min(ans, t * c[start].second);
    start++;
  }
  cout << ans << endl;
}
