import sys
import math

def get_divisors(n):
    divisors = set()
    for i in range(1, int(math.isqrt(n)) + 1):
        if n % i == 0:
            divisors.add(i)
            divisors.add(n // i)
    return sorted(divisors)

def factorize(n):
    factors = []
    i = 2
    while i * i <= n:
        while n % i == 0:
            factors.append(i)
            n //= i
        i += 1
    if n > 1:
        factors.append(n)
    return factors

def generate_factor_sequences(n, current, start, memo):
    if n == 1:
        return [[]]
    if (n, start) in memo:
        return memo[(n, start)]
    sequences = []
    i = start
    while i * i <= n:
        if n % i == 0:
            if i >= start:
                for seq in generate_factor_sequences(n // i, current + [i], i, memo):
                    sequences.append([i] + seq)
        i += 1
    if n >= start:
        sequences.append([n])
    memo[(n, start)] = sequences
    return sequences

def main():
    N, M, A, B = map(int, sys.stdin.readline().split())
    forbidden = set(map(int, sys.stdin.readline().split()))
    forbidden_set = set(forbidden)
    
    divisors = get_divisors(N)
    min_cost = float('inf')
    
    for P in divisors:
        if P == 0:
            continue
        if P == 1:
            continue
        factors = factorize(P)
        memo = {}
        sequences = generate_factor_sequences(P, [], 2, memo)
        for seq in sequences:
            product = 1
            valid = True
            for i in range(len(seq)):
                f = seq[i]
                prev_product = product
                for t in range(2, f + 1):
                    x = prev_product * t
                    if x in forbidden_set:
                        valid = False
                        break
                if not valid:
                    break
                product *= f
            if not valid:
                continue
            K = N // P
            if K < 1:
                continue
            final_product = product
            for t in range(2, K + 1):
                x = final_product * t
                if x in forbidden_set:
                    valid = False
                    break
            if not valid:
                continue
            cost = 0
            for f in seq:
                cost += (f - 1) * A + B
            cost += (K - 1) * A
            if cost < min_cost:
                min_cost = cost
    
    if min_cost != float('inf'):
        print(min_cost)
    else:
        print(-1)

if __name__ == '__main__':
    main()