#include <bits/stdc++.h>
using namespace std;
const int N = 200010;
int a[N], costa[N], c[N], costc[N];
int main() {
  int n, m, k;
  scanf("%d %d %d", &n, &m, &k);
  int x, s;
  scanf("%d %d", &x, &s);
  for (int i = 0; i < m; i++) {
    scanf("%d", a + i);
  }
  for (int i = 0; i < m; i++) {
    scanf("%d", costa + i);
  }
  a[m] = x;
  costa[m] = 0;
  m++;
  for (int i = 0; i < k; i++) {
    scanf("%d", c + i);
  }
  for (int i = 0; i < k; i++) {
    scanf("%d", costc + i);
  }
  long long ans = (long long)x * (long long)n;
  for (int i = 0; i < m; i++) {
    if (costa[i] > s) continue;
    int xx = a[i];
    int ss = s - costa[i];
    int p = n;
    int pos = upper_bound(costc, costc + k, ss) - costc - 1;
    if (pos >= 0) p = max(p - c[pos], 0);
    long long cur = (long long)p * (long long)xx;
    ans = min(ans, cur);
  }
  printf("%lld\n", ans);
  return 0;
}
