#include <bits/stdc++.h>
using namespace std;
long long N, P, Q;
int main() {
  cin >> N >> P >> Q;
  long long res = 0;
  for (int i = 0; i < N; i++) {
    long long c;
    cin >> c;
    if (Q * P + (long long)(N - i - 1) * P < c) {
      res += c;
      Q--;
    } else {
      res += Q * P;
      Q++;
    }
  }
  cout << res << endl;
}
