#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, k, x;
  cin >> n >> k >> x;
  int *an = new int[n];
  for (int i = 0; i < n; i++) cin >> *(an + i);
  int s = 0;
  for (int i = 0; i < n - k; i++) s += an[i];
  cout << s + k * x << endl;
  return 0;
}
