#include <bits/stdc++.h>
using namespace std;
const int MAX = 2e5 + 7;
int m, k;
long long n, x, s, a[MAX], b[MAX], c[MAX], d[MAX];
int main() {
  ios::sync_with_stdio(0);
  cin.tie(0);
  cin >> n >> m >> k >> x >> s;
  for (int i = 1; i <= m; ++i) {
    cin >> a[i];
  }
  for (int i = 1; i <= m; ++i) {
    cin >> b[i];
  }
  for (int i = 1; i <= k; ++i) {
    cin >> c[i];
  }
  for (int i = 1; i <= k; ++i) {
    cin >> d[i];
  }
  long long res = x * n;
  for (int i = 1; i <= m; ++i) {
    int l = 1, r = k;
    while (l <= r) {
      int mid = (l + r) / 2;
      if (b[i] + d[mid] <= s) {
        l = mid + 1;
      } else {
        r = mid - 1;
      }
    }
    long long numPrep = c[r];
    if (numPrep == n) {
      res = 0;
      break;
    }
    long long prepTime = x * n;
    if (b[i] <= s) {
      prepTime = a[i] * (n - numPrep);
    }
    res = min(prepTime, res);
  }
  long long mxNumPrep = -1;
  for (int i = 1; i <= k; ++i) {
    if (d[i] <= s) {
      mxNumPrep = max(mxNumPrep, c[i]);
    } else {
      break;
    }
  }
  res = min(x * (n - mxNumPrep), res);
  cout << res << "\n";
  return 0;
}
