#include <bits/stdc++.h>
using namespace std;
const int MX = 10000000;
const long long INF = 1000000000000000000;
int main(){
  int T;
  cin >> T;
  int X, A;
  cin >> X >> A;
  int Y, B;
  cin >> Y >> B;
  vector<long long> d(MX * 2 + 1, -1);
  priority_queue<pair<long long, int>, vector<pair<long long, int>>, greater<tuple<long long, int>>> pq;
  pq.push(make_pair(0, MX));
  while (!pq.empty()){
    long long c = pq.top().first;
    int v = pq.top().second;
    pq.pop();
    if (d[v] == -1){
      d[v] = c;
      if (v + A <= MX * 2){
        if (d[v + A] == -1){
          pq.push(make_pair(c + X, v + A));
        }
      }
      if (v - B >= 0){
        if (d[v - B] == -1){
          pq.push(make_pair(c + Y, v - B));
        }
      }
    }
  }
  long long ans = INF;
  for (int i = 0; i <= MX + T; i++){
    if (d[i] != -1){
      ans = min(ans, d[i] + (MX + T - i));
    }
  }
  cout << ans << endl;
}