#include <bits/stdc++.h>
using namespace std;
int main() {
  ios_base::sync_with_stdio(false);
  int n, k, x;
  cin >> n >> k >> x;
  vector<int> a(n);
  for (int i = 0; i < n; ++i) {
    int t;
    cin >> t;
    a[i] = t;
  }
  cout << endl;
  int rez = 0;
  for (int j = 0; j < n - k; ++j) {
    rez += a[j];
  }
  for (int l = n - k; l < n; ++l) {
    rez += min(x, a[l]);
  }
  cout << rez;
  return 0;
}
