#include <bits/stdc++.h>
using namespace std;

using ll = long long;
using ull = unsigned long long;
using ld = long double;
template<class t> using vc = vector<t>;
template<class t> using vvc = vc<vc<t>>;
using pi = pair<int,int>;
using pl = pair<ll,ll>;
using vi = vc<int>;
using vvi = vvc<int>;
using vl = vc<ll>;
using vvl = vvc<ll>;

#define rep(i,a,b) for (int i = (int)(a); i < (int)(b); i++)
#define irep(i,a,b) for (int i = (int)(a); i > (int)(b); i--)
#define all(a) a.begin(),a.end()
#define print(n) cout << n << '\n'
#define pritn(n) print(n)
#define printv(n,a) {copy(all(n),ostream_iterator<a>(cout," ")); cout<<"\n";}
#define printvv(n,a) {for(auto itr:n) printv(itr,a);}
#define rup(a,b) (a+b-1)/b
#define input(A,N) rep(i,0,N) cin>>A[i]
#define chmax(a,b) a = max(a,b)
#define chmin(a,b) a = min(a,b)


int main(){
    cout << fixed << setprecision(15);
    
    ll t;
    cin>>t;
    ll x,a,y,b;
    cin>>x>>a>>y>>b;
    ll ans = (ll(1e14));
    if(t>=0){
        ans = t;
        ll ni = 0;
        ni--;
        while(1){
            ni++;
            ll now = ni * y;
            if(now>ans) break;
            ll need = t + ni * b;
            chmin(ans,need+now);
            ll d = need / a;
            ll ni = need % a;
            chmin(ans,now+ni+d*x);
        }
    }else{
        ll now = 0;
        ll ni = 0;
        while(now>t){
            now -= b;
            ni++;
        }
        ni--;
        now += b;
        while(1){
            ni++;
            now -= b;
            ll nn = ni * y; 
            //cout<<ans<<" "<<nn<<" "<<ni<<endl;
            if(nn>ans) break;
            ll need = t - now;
            chmin(ans,nn+need);
            ll d = need / a;
            ll ni = need % a;
            chmin(ans,nn+ni+d*x);
        }
    }
    print(ans);
    //system("pause");
    return 0;
}