#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, k, x;
  int a[105];
  cin >> n >> k >> x;
  int Sum = 0;
  for (int i = 1; i <= n; i++) {
    cin >> a[i];
  }
  for (int i = 1; i <= n - k; i++) {
    Sum += a[i];
  }
  Sum += k * x;
  cout << Sum << endl;
}
