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