from collections import *
N,M,A,B=map(int,input().split())
C=sorted(list(map(int,input().split())))
inf=10**18
d=defaultdict(lambda:inf)
z=defaultdict(lambda:inf)
d[1]=0
D=set()
for i in range(1,int(N**0.5)+1):
 if N%i==0:D.add(i);D.add(N//i)
D=sorted(list(D))
K=len(D)
for i in range(K):
 v=D[i]
 for j in range(M):
  if C[j]%v==0:z[v]=min(z[v],C[j])
 y=inf
 for j in range(i):
  x=D[j]
  if v%x==0 and z[x]>v:
   y=min(y,d[x]+B*(i<K-1)+(v//x-1)*A)
  d[v]=y*(i!=0)
print(d[N] if d[N]!=inf else -1)