mod = 998244353


def main():
    import sys
    input = sys.stdin.readline

    def PrimeDecomposition(N):
        ret = {}
        n = int(N ** 0.5)
        for d in range(2, n + 1):
            while N % d == 0:
                if d not in ret:
                    ret[d] = 1
                else:
                    ret[d] += 1
                N //= d
            if N == 1:
                break
        if N != 1:
            ret[N] = 1
        return ret

    N, M, A, B = map(int, input().split())
    C = list(map(int, input().split()))

    P = PrimeDecomposition(N)
    div_list = [1]
    for p in P:
        e = P[p]
        div_list_new = []
        p_list = [p ** i for i in range(e + 1)]
        for d in div_list:
            for pp in p_list:
                div_list_new.append(d * pp)
        div_list = div_list_new

    div_list.sort(reverse=True)
    L = len(div_list)

    ok_min = [10 ** 10] * L
    for i in range(L):
        di = div_list[i]
        for c in C:
            if c % di == 0:
                ok_min[i] = min(ok_min[i], c)

    dp = [float("inf")] * L
    dp[0] = 0
    for i in range(L):
        di = div_list[i]
        for j in range(i+1, L):
            dj = div_list[j]
            if di % dj:
                continue
            if di >= ok_min[j]:
                continue
            dp[j] = min(dp[j], dp[i] + B + A * (di // dj - 1))
    if dp[-1] < 10 ** 18:
        print(dp[-1] - B)
    else:
        print(-1)
    # print(dp, div_list)


if __name__ == '__main__':
    main()