#include <bits/stdc++.h>
using namespace std;
int main() {
  ios_base::sync_with_stdio(false);
  int n, k, x;
  cin >> n >> k >> x;
  int v[n];
  for (int i = 0; i < n; i++) cin >> v[i];
  int time = 0;
  while (k--) {
    n--;
    time += x;
  }
  while (n) {
    n--;
    time += v[n];
  }
  cout << time;
}
