#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <cmath>
#include <algorithm>
#define IOS ios::sync_with_stdio(false)
using namespace std;
#define inf (0x3f3f3f3f)
typedef long long int LL;#include <iostream>
#include <sstream>
#include <vector>
#include <set>
#include <map>
#include <queue>
#include <string>
const int maxn = 1e6 + 20;
LL a[maxn];
LL b[maxn];
struct node {LL c, d;node(LL cc, LL dd) : c(cc), d(dd) {}node() {}bool operator < (const struct node & rhs) const {return d < rhs.d;}
}arr[maxn];
struct tt {LL tim, lef;LL id;
}ff[maxn];
struct bug {LL a, b;int id;bug() {}bug(LL aa, LL bb) : a(aa), b(bb) {}bool operator < (const struct bug & rhs) const {if (b != rhs.b) return b < rhs.b;else return a > rhs.a; //这个按大排
    }
}gg[maxn];
void work() {LL n, m, k;cin >> n >> m >> k;LL x, limit;cin >> x >> limit;for (int i = 1; i <= m; ++i) {cin >> a[i];gg[i].a = a[i];}for (int i = 1; i <= m; ++i) {cin >> b[i];gg[i].b = b[i];gg[i].id = i;}sort(gg + 1, gg + 1 + m);for (int i = 1; i <= k; ++i) {cin >> arr[i].c;}for (int i = 1; i <= k; ++i) {cin >> arr[i].d;}LL ans = n * x;int lenff = 0;
//    cout << x << endl;for (int i = 1; i <= m; ++i) {if (b[i] > limit) continue;++lenff;ff[lenff].tim = n * a[i];ff[lenff].lef = limit - b[i];ff[lenff].id = i;}
//    for (int i = 1; i <= lenff; ++i) {
//        cout << ff[i].tim << " " << ff[i].lef << endl;
//    }for (int i = 1; i <= lenff; ++i) {ans = min(ans, ff[i].tim);if (ff[i].lef < arr[1].d) continue;int pos = upper_bound(arr + 1, arr + 1 + k, node(0L, ff[i].lef)) - arr;pos--;LL t = ff[i].tim - arr[pos].c * a[ff[i].id];ans = min(ans, t);}lenff = 0;for (int i = 1; i <= k; ++i) {if (arr[i].d > limit) continue;++lenff;ff[lenff].lef = limit - arr[i].d;ff[lenff].tim = (n - arr[i].c) * x;ff[lenff].id = n - arr[i].c;}for (int i = 1; i <= lenff; ++i) {ans = min(ans, ff[i].tim);if (ff[i].lef < gg[1].b) continue;int pos = upper_bound(gg + 1, gg + 1 + m, bug(0, ff[i].lef)) - gg;pos--;LL t = ff[i].id * a[gg[pos].id];ans = min(ans, t);}cout << ans << endl;
}int main() {
#ifdef localfreopen("data.txt","r",stdin);
#endifIOS;work();return 0;
}