T = int(input())
X, A = map(int, input().split())
Y, B = map(int, input().split())

if T >= 0:
    ans = T

    cnt = 0
    while cnt * Y < T:
        t = cnt * B + T
        q, r = divmod(t,A)
        tmp = cnt*Y + q * X + r
        ans = min(ans, tmp)
        cnt += 1

    print(ans)

else:

    e = (abs(T) + (B-1)) // B
    ans = e * Y + (T-(-e*B))

    cnt = e
    while cnt * Y < ans:
        t = T - (-cnt*B)
        q, r = divmod(t,A)
        tmp = cnt * Y + q * X + r
        ans = min(ans, tmp)
        cnt += 1

    print(ans)