from collections import *

def div(n):
    i = 1
    SS = set()
    while i * i <= n:
        if n % i == 0:
            SS.add(i)
            SS.add(n//i)
        i += 1
    return sorted(list(SS))    

N, M, A, B = map(int, input().split())
C = sorted(list(map(int, input().split())))
inf = 10 ** 18
dic = defaultdict(lambda : inf)
minv = defaultdict(lambda : inf)
dic[1] = 0
D = div(N)
K = len(D)
for i in range(K):
    for j in range(M):
        if C[j] % D[i] == 0:
            minv[D[i]] = min(minv[D[i]], C[j])

for i in range(1, K):
    val = inf
    for j in range(i):
        if D[i] % D[j] == 0 and minv[D[j]] > D[i]:
            val = min(val, dic[D[j]] + B * int(i<K-1) + (D[i]//D[j] - 1) * A)
    dic[D[i]] = val

print(dic[N]) if dic[N] != inf else print(-1)