#include <bits/stdc++.h>
using namespace std;
const long long inf = 0x7f7f7f7f7f7f7f7fll;
const int N = 200005;
int a[N], b[N], c[N], d[N];
int main() {
  int n, m, k, x, s, i, j;
  long long ans = inf;
  scanf("%d%d%d%d%d", &n, &m, &k, &x, &s);
  for (i = 0; i < m; ++i) scanf("%d", a + i);
  a[m] = x;
  for (i = 0; i < m; ++i) scanf("%d", b + i);
  b[m++] = 0;
  ++k;
  for (i = 1; i < k; ++i) scanf("%d", c + i);
  c[0] = 0;
  for (i = 1; i < k; ++i) scanf("%d", d + i);
  d[0] = 0;
  for (i = 0; i < m; ++i) {
    int j = upper_bound(d, d + k, s - b[i]) - d;
    if (!j) continue;
    ans = min(ans, 1ll * a[i] * (n - c[j - 1]));
  }
  printf("%I64d", ans == inf ? -1 : ans);
  return 0;
}
