def Wholesale(N, A, B, C, D):
    res = N
    for x in range((N + A - 1) // A + 1):

        if x * A < N:
            y = (N - x * A) // C
        else:
            y = 0

        if N - x * A - y * C > 0:
            z = N - x * A - y * C
        else:
            z = 0

        if res > min(x * B + y * D + z, x * B + (y + 1) * D):
            res = min(x * B + y * D + z, x * B + (y + 1) * D)
    return res

N = int(input())
A = int(input())
B = int(input())
C = int(input())
D = int(input())
print(Wholesale(N, A, B, C, D))