#include <bits/stdc++.h>
using namespace std;
struct custom_hash {
  static uint64_t splitmix64(uint64_t x) {
    x += 0x9e3779b97f4a7c15;
    x = (x ^ (x >> 30)) * 0xbf58476d1ce4e5b9;
    x = (x ^ (x >> 27)) * 0x94d049bb133111eb;
    return x ^ (x >> 31);
  }
  size_t operator()(uint64_t x) const {
    static const uint64_t FIXED_RANDOM =
        chrono::steady_clock::now().time_since_epoch().count();
    return splitmix64(x + FIXED_RANDOM);
  }
};
int main() {
  cin.sync_with_stdio(0);
  cin.tie(0);
  cin.exceptions(cin.failbit);
  long long a, b, c, d, e, f;
  cin >> a >> b >> c >> d >> e >> f;
  long long ans = 0;
  for (long long dd = 0; dd <= d; dd++) {
    long long cand = min(a, dd) * e + min(b, min(c, d - dd)) * f;
    ans = max(cand, ans);
  }
  cout << ans << endl;
}
