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