#include <bits/stdc++.h>
using namespace std;
long long n, d, ma, m[2], nn[2];
pair<long long, long long> a[2][200069], sk[2][200069];
int main() {
  long long i, j, ii, mn = 5e18;
  scanf("%lld%lld%lld%lld%lld", &n, m, m + 1, &d, &ma);
  sk[0][1] = {0, -d};
  sk[1][1] = {0, 0};
  for (ii = 0; ii < 2; ii++) {
    for (i = 1; i <= m[ii]; i++) {
      scanf("%lld", &a[ii][i].second);
    }
    for (i = 1; i <= m[ii]; i++) {
      scanf("%lld", &a[ii][i].first);
      if (!ii) {
        a[ii][i].second *= -1;
      }
    }
    sort(a[ii] + 1, a[ii] + m[ii] + 1);
    nn[ii] = 1;
    for (i = 1; i <= m[ii]; i++) {
      if (a[ii][i].second > sk[ii][nn[ii]].second) {
        nn[ii]++;
        sk[ii][nn[ii]] = a[ii][i];
      }
    }
  }
  for (j = nn[1], i = 1; i <= nn[0] && sk[0][i].first <= ma; i++) {
    for (; sk[0][i].first + sk[1][j].first > ma; j--)
      ;
    mn = min(mn, max(n - sk[1][j].second, 0ll) * -sk[0][i].second);
  }
  printf("%lld\n", mn);
}
