#include "bits/stdc++.h" using namespace std; #define int long long #define FOR(i, a, b) for(int i=(a);i<(b);i++) #define RFOR(i, a, b) for(int i=(b-1);i>=(a);i--) #define REP(i, n) for(int i=0; i<(n); i++) #define RREP(i, n) for(int i=(n-1); i>=0; i--) #define REP1(i, n) for(int i=1; i<=(n); i++) #define RREP1(i, n) for(int i=(n); i>=1; i--) #define ALL(a) (a).begin(),(a).end() #define UNIQUE_SORT(l) sort(ALL(l)); l.erase(unique(ALL(l)), l.end()); #define CONTAIN(a, b) find(ALL(a), (b)) != (a).end() #define out(...) printf(__VA_ARGS__) #define chmax(a,b) a = max(a,b) #define chmin(a,b) a = min(a,b) #if DEBUG #define debug(...) //printf(__VA_ARGS__) #else #define debug(...) /* ... */ #endif void solve(); signed main() { #if DEBUG std::ifstream in("input.txt"); std::cin.rdbuf(in.rdbuf()); #endif cin.tie(0); ios::sync_with_stdio(false); solve(); return 0; } /*================================*/ #if DEBUG #define SIZE 100 #else #define SIZE 123450 #endif int N,K,X,Y,A[SIZE]; int calc(int r) { int base = r * K + 1; int cnt = 0; REP(i,N) { int remain = A[i]-base; if (remain <= 0) continue; cnt += (remain+K-1)/K; } int ret = r*Y+cnt*X; debug("X(%lld) * %lld + Y(%lld) * %lld = %lld\n", X,cnt, Y,r, ret); return ret; } void solve() { cin>>N>>K>>X>>Y; REP(i,N)cin>>A[i]; int l = 0, r = 1e9; REP(i,100) { int ll = (l+l+r)/3; int rr = (l+r+r)/3; if (calc(ll) < calc(rr)) r = rr; else l = ll; } int ans = 1e9; debug("%lld ~ %lld\n", l,r); FOR(n,l,r+1) { debug("--"); chmin(ans, calc(n)); } cout << ans << endl; }