#include<bits/stdc++.h>
#include<atcoder/all>
using namespace std;
using namespace atcoder;
typedef long long int ll;
typedef long double ld;
#define FOR(i,l,r) for(ll i=l;i<r;i++)
#define REP(i,n) FOR(i,0,n)
#define RFOR(i,l,r) for(ll i=r-1;i>=l;i--)
#define RREP(i,n) RFOR(i,0,n)
#define ALL(x) x.begin(),x.end()
#define PA pair<ll,ll>
#define F first
#define S second
#define BS(A,x) binary_search(ALL(A),x)
#define LB(A,x) (ll)(lower_bound(ALL(A),x)-A.begin())
#define UB(A,x) (ll)(upper_bound(ALL(A),x)-A.begin())
#define COU(A,x) (UB(A,x)-LB(A,x))
#define sz(c) ((ll)(c).size())
/*
#include<boost/multiprecision/cpp_int.hpp>
namespace mp=boost::multiprecision;
using Bint=mp::cpp_int;
*/
template<typename T>using min_priority_queue=priority_queue<T,vector<T>,greater<T>>;
template<typename T1,typename T2>ostream&operator<<(ostream&os,pair<T1,T2>&p){os<<p.F<<" "<<p.S;return os;}
template<typename T1,typename T2>istream&operator>>(istream&is,pair<T1,T2>&p){is>>p.F>>p.S;return is;}
template<typename T>ostream&operator<<(ostream&os,vector<T>&v){REP(i,sz(v))os<<v[i]<<(i+1!=sz(v)?" ":"");return os;}
template<typename T>istream&operator>>(istream&is,vector<T>&v){for(T&in:v)is>>in;return is;}
template<class T>bool chmax(T&a,T b){if(a<b){a=b;return 1;}return 0;}
template<class T>bool chmin(T&a,T b){if(b<a){a=b;return 1;}return 0;}
ld dist(ld x1,ld y1,ld x2,ld y2){return sqrtl((x1-x2)*(x1-x2)+(y1-y2)*(y1-y2));}
//using mint=modint1000000007;
using mint=modint998244353;
//const ll mod=1000000007;
const ll mod=998244353;
//using mint=modint;
ostream&operator<<(ostream&os,mint&a){os<<a.val();return os;}
int main(){
  ll N,M,A,B;cin>>N>>M>>A>>B;
  vector<ll>C(M);cin>>C;
  
  set<ll>s;ll d=1;
  while(d*d<=N){if(N%d==0)s.insert(d),s.insert(N/d);d++;}
  vector<ll>D;for(auto i:s)D.emplace_back(i);
  
  ll L=sz(D);
  vector<ll>DP(L,1e18);DP[0]=0;
  vector<ll>W(L,1e18);
  REP(i,L)REP(j,M)if(C[j]%D[i]==0)chmin(W[i],C[j]);
  REP(i,L)if(DP[i]<1e18){
    FOR(j,i+1,L)if(D[j]%D[i]==0&&W[i]>D[j])chmin(DP[j],DP[i]+(D[j]/D[i]-1)*A+B);
  }
  if(DP[L-1]==1e18)DP[L-1]=B-1;
  cout<<DP[L-1]-B<<endl;
  
  return 0;
}