#include <bits/stdc++.h>
using namespace std;
const int mod = 1E9 + 7;
const int maxn = 2E5 + 10;
const int inf = 0x3f3f3f3f;
int a[maxn], b[maxn], c[maxn], d[maxn];
int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  long long n, m, k, x, s;
  cin >> n >> m >> k;
  cin >> 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 ans = (n - c[upper_bound(d + 1, d + k + 1, s) - d - 1]) * x;
  for (int i = 1; i <= m; i++) {
    if (b[i] > s) continue;
    ans = min(ans,
              (n - c[upper_bound(d + 1, d + k + 1, s - b[i]) - d - 1]) * a[i]);
  }
  cout << ans << endl;
}
