#include <bits/stdc++.h>
using namespace std;
int main() {
  long long n, m, k, x, s, c, ans = 0;
  long long a[200007], b[200007], ai[200007], bi[200007];
  cin >> n >> m >> k >> x >> s;
  ans = x * n;
  for (int i = 1; i <= m; i++) cin >> a[i];
  for (int i = 1; i <= m; i++) {
    cin >> ai[i];
    if (ai[i] <= s) {
      ans = min(ans, a[i] * n);
    }
  }
  for (int i = 1; i <= k; i++) cin >> b[i];
  for (int i = 1; i <= k; i++) {
    cin >> bi[i];
    if (bi[i] <= s) ans = min(ans, (n - b[i]) * x);
  }
  for (int i = 1; i <= m; i++) {
    int l = 0, r = k + 1;
    while (r - l > 1) {
      int f = (r + l) / 2;
      if (s >= ai[i] + bi[f])
        l = f;
      else
        r = f;
    }
    if (l != 0) {
      if (ai[i] + bi[l] <= s) ans = min(ans, (n - b[l]) * a[i]);
    }
  }
  cout << ans;
  return 0;
}
