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