#include<bits/stdc++.h> using namespace std; const int N=1e5+10; int n,b,x; int c[N]; long long q(int y){ long long ans=0; for(int i=1;i<=n;i++){ long long yu=c[i]/y; ans+=(long long)(c[i]%y)*(yu+1)*(c[i]-(yu+1))*b; ans+=(long long)(y-(c[i]%y))*yu*(c[i]-yu)*b; } ans/=2; ans-=(long long)x*(y-1); return ans; } int main(){ scanf("%d%d%d",&n,&b,&x); int sum=0; for(int i=1;i<=n;i++){ scanf("%d",&c[i]); sum+=c[i]; } int l=1,r=sum; while(l<r){ int mid=(l+r)/2; if(q(mid)<q(mid+1)) l=mid+1; else if(q(mid)<q(mid-1)) r=mid-1; else l=mid,r=mid; } printf("%lld",q(l)); return 0; }