#define _USE_MATH_DEFINES
#include <bits/stdc++.h>
using namespace std;
#define FOR(i,m,n) for(int i=(m);i<(n);++i)
#define REP(i,n) FOR(i,0,n)
#define ALL(v) (v).begin(),(v).end()
using ll = long long;
constexpr int INF = 0x3f3f3f3f;
constexpr long long LINF = 0x3f3f3f3f3f3f3f3fLL;
constexpr double EPS = 1e-8;
constexpr int MOD = 998244353;
// constexpr int MOD = 1000000007;
constexpr int DY4[]{1, 0, -1, 0}, DX4[]{0, -1, 0, 1};
constexpr int DY8[]{1, 1, 0, -1, -1, -1, 0, 1};
constexpr int DX8[]{0, -1, -1, -1, 0, 1, 1, 1};
template <typename T, typename U>
inline bool chmax(T& a, U b) { return a < b ? (a = b, true) : false; }
template <typename T, typename U>
inline bool chmin(T& a, U b) { return a > b ? (a = b, true) : false; }
struct IOSetup {
  IOSetup() {
    std::cin.tie(nullptr);
    std::ios_base::sync_with_stdio(false);
    std::cout << fixed << setprecision(20);
  }
} iosetup;

int main() {
  int t, x, a, y, b; cin >> t >> x >> a >> y >> b;
  ll ans = LINF;
  if (t < 0) {
    t = -t;
    for (int i = (t + b - 1) / b; i <= (t + b - 1) / b + a; ++i) {
      const ll rem = 1LL * i * b - t;
      chmin(ans, 1LL * i * y + rem / a * x + rem % a);
    }
  } else {
    for (int i = 0; i <= a; ++i) {
      const ll len = t + 1LL * i * b;
      chmin(ans, 1LL * y * i + len / a * x + len % a);
    }
  }
  cout << ans << '\n';
  return 0;
}