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