from heapq import heappush, heappop
import sys
input = sys.stdin.readline

def divisor(n):
    divisors = []
    i = 1
    while i * i < n:
        if n % i == 0:
            divisors.append(i)
            divisors.append(n // i)
        i += 1
    if i * i == n:
        divisors.append(i)
    divisors.sort()
    return divisors

N, M, A, B = map(int, input().split())
C = list(map(int, input().split()))
C.sort()
div = divisor(N)
leastmultiple = {}
for d in div:
    for c in C:
        if c % d == 0:
            leastmultiple[d] = c
            break

dist = {}
heap = [(0, N)]
dist[N] = 0
while heap:
    d, n = heappop(heap)
    if n == 1:
        print(d-B)
        exit()
    if dist[n] < d:
        continue
    for m in div:
        if m >= n:
            break
        if m in leastmultiple and leastmultiple[m] < n:
            continue
        nd = d + (n//m-1) * A + B
        if m not in dist or nd < dist[m]:
            dist[m] = nd
            heappush(heap, (nd, m))
print(-1)