#include <bits/stdc++.h>   using namespace std;   int main() {     long long n, k, B, c;     cin >> n >> k >> B >> c;     long long a[n];     for (int i = 0; i < n; i++) cin >> a[i];     long long x = *min_element(a, a + n);     for (int i = 0; i < n; i++) a[i] = a[i] - x;     B = min(B, 5 * c);     long long ans = 1e18;     for (int t = 0; t < 5; t++) {       pair<long long, long long> b[n];       for (int i = 0; i < n; i++) {         b[i] = {a[i], 0};         while (b[i].first % 5 != t) {           b[i].first++;           b[i].second += c;         }         b[i].first /= 5;       }       sort(b, b + n);       priority_queue<long long> G;       long long suma = 0;       for (int i = 0; i < n; i++) {         if (G.size() >= k - 1) {           ans = min(ans, b[i].second + b[i].first * B * (k - 1) + suma);         }         G.push(b[i].second - b[i].first * B);         suma += b[i].second - b[i].first * B;         while (G.size() >= k) {           suma -= G.top();           G.pop();         }       }     }     cout << ans <<   n ;   }   