#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define eb emplace_back
#define pb push_back
#define fi first
#define se second
#define ii pair<int,int>
#define ve vector
#define all(x) x.begin(), x.end()
#define fo(i,a,b) for (int i=(a); i<=(b); ++i)
#define fd(i,a,b) for (int i=(a); i>=(b); --i)
#define maxi(a, b) a = max(a, b)
#define mini(a, b) a = min(a, b)
#define _ << ' ' <<
const int N = 2e7+5, inf = 1e9+10, mod = 1e9+7;
const ll inf64=4e18+1;
/**
**/
ll n, a, b, c, d;
ll cd(ll x, ll y) {
return max(0ll,(x+y-1)/y);
}
void sol() {
cin >> n >> a >> b >> c >> d;
ll ans = inf64;
fo(i,0,1000000) if (1ll*a*i<=n) mini(ans,1ll*i*b+cd(n-1ll*i*a,c)*d);
fo(i,0,1000000) if (1ll*c*i<=n) mini(ans,1ll*i*d+cd(n-1ll*i*c,a)*b);
cout<<ans;
}
signed main(){
ios::sync_with_stdio(0); cin.tie(0);
if(fopen("A.inp","r")) {
freopen("A.inp","r",stdin);
freopen("A.out","w",stdout);
}
int tc = 1; // cin >> tc;
fo(i,1,tc) sol();
return 0;
}
