#include <bits/stdc++.h>
using namespace std;
const int MAX = 200010;
const double eps = 1e-6;
long long n, m, k;
long long a[MAX], b[MAX], c[MAX], d[MAX];
int main() {
  int i, j;
  while (~scanf("%lld%lld%lld", &n, &m, &k)) {
    long long x, s;
    scanf("%lld%lld", &x, &s);
    for (i = 1; i <= m; i++) scanf("%lld", &a[i]);
    for (i = 1; i <= m; i++) scanf("%lld", &b[i]);
    for (i = 1; i <= k; i++) scanf("%lld", &c[i]);
    for (i = 1; i <= k; i++) scanf("%lld", &d[i]);
    long long temp = 0;
    long long ans = n * x;
    long long sum = n * x;
    for (i = 1; i <= m; i++) {
      if (b[i] <= s) {
        temp = s - b[i];
        long long l = 1, r = k;
        long long res = 0;
        if (d[1] > temp) {
          ans = min(ans, a[i] * n);
          continue;
        }
        while (l < r) {
          long long mid = l + (r - l + 1) / 2;
          if (d[mid] > temp)
            r = mid - 1;
          else {
            res = max(res, c[mid]);
            l = mid;
          }
        }
        res = c[l];
        if (res > n) res = n;
        sum = (n - res) * a[i];
        ans = min(ans, sum);
      }
    }
    for (i = 1; i <= k; i++) {
      if (d[i] <= s) ans = min(ans, (n - c[i]) * x);
    }
    printf("%lld\n", ans);
  }
  return 0;
}
