#include using namespace std; using ll = long long; using ull = unsigned long long; using ld = long double; template using vc = vector; template using vvc = vc>; using pi = pair; using pl = pair; using vi = vc; using vvi = vvc; using vl = vc; using vvl = vvc; #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(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; 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) 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; }