#include <bits/stdc++.h>
using namespace std;
long long n, m, k, s, x;
long long a[200005], b[200005], c[200005], d[200005];
int main() {
  cin >> n >> m >> k;
  cin >> x >> s;
  for (int i = 0; i < m; i++) cin >> a[i];
  for (int i = 0; i < m; i++) cin >> b[i];
  for (int i = 0; i < k; i++) cin >> c[i];
  for (int i = 0; i < k; i++) cin >> d[i];
  long long ans = (n - c[upper_bound(d, d + k, s) - d - 1]) * x;
  for (int i = 0; i < m; i++) {
    if (b[i] <= s)
      ans =
          min(ans, (long long)(n - c[upper_bound(d, d + k, s - b[i]) - d - 1]) *
                       a[i]);
  }
  cout << ans << endl;
  return 0;
}
