#include <bits/stdc++.h>
using namespace std;
template <class T>
void debug(T a) {
  for (auto i : a) cout << i << endl;
}
signed main() {
  long long n, p, q;
  cin >> n >> p >> q;
  vector<long long> a;
  for (long long i = 0; i < (long long)n; i++) {
    long long c;
    cin >> c;
    a.push_back(c);
  }
  long long ans = 0;
  for (long long i = 0; i < (long long)n; i++) {
    if (a[i] - q * p >= (n - i - 1) * p) {
      ans += a[i];
      q--;
    } else {
      ans += q * p;
      q++;
    }
  }
  cout << ans << endl;
}
