#include "bits/stdc++.h"
using namespace std;
#define int long long
const int sz = 2e5 + 5;
const int inf = 1e18;
void solve()
{
int n, a, b, c, d;
cin >> n >> a >> b >> c >> d;
if (c * b > a * d) swap(a, c), swap(b, d);
int mn = inf;
for(int i = 0; i < a; i++)
{
int x = n - i * c;
int cnt = x > 0 ? (x - 1) / a + 1 : 0;
mn = min(mn, cnt * b + i * d);
}
cout << mn << endl;
}
signed main()
{
ios_base::sync_with_stdio(false);
cin.tie(nullptr);
cout.tie(nullptr);
int t = 1;
// cin >> t;
for(int i = 1; i <= t; i++) solve();
}
