#include<iostream> #include<vector> #include<algorithm> using namespace std; int N,M,A,B; int C[5000]; int main() { cin>>N>>M>>A>>B; for(int i=0;i<M;i++)cin>>C[i]; sort(C,C+M); vector<int>dv; for(int i=1;i*i<=N;i++)if(N%i==0) { dv.push_back(i); if(i<N/i)dv.push_back(N/i); } sort(dv.begin(),dv.end()); vector<long long>dp(dv.size(),(long long)1e18); dp[0]=0; vector<int>tmp; for(int i=0;i<dv.size();i++) { tmp.clear(); for(int j=0;j<M;j++)if(C[j]%dv[i]==0)tmp.push_back(C[j]); for(int j=i+1;j<dv.size();j++)if(dv[j]%dv[i]==0) { if(lower_bound(tmp.begin(),tmp.end(),dv[i])==upper_bound(tmp.begin(),tmp.end(),dv[j])) { dp[j]=min(dp[j],dp[i]+B+dv[j]/dv[i]*(long long)A-A); } } } if(dp[dv.size()-1]==(long long)1e18)cout<<-1<<endl; else cout<<dp[dv.size()-1]-B<<endl; }