#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, m, k;
  cin >> n >> m >> k;
  int total = 0;
  for (int i = 1; i <= n; ++i) {
    int temp;
    cin >> temp;
    if (n - i < m) {
      total += min(k, temp);
    } else {
      total += temp;
    }
  }
  cout << total << endl;
  return 0;
}
