#include <bits/stdc++.h>
using namespace std;
int main() {
  long long int n, k, x, a, answer;
  answer = 0;
  cin >> n >> k >> x;
  for (int i = 0; i < n; i++) {
    cin >> a;
    if (i < (n - k)) {
      answer = answer + a;
    } else {
      answer = answer + x;
    }
  }
  cout << answer;
  return 0;
}
