#include <bits/stdc++.h>
using namespace std;
int n, k, x, miniSum, num;
int main() {
  cin >> n >> k >> x;
  while (n--) {
    cin >> num;
    if (n < k)
      miniSum += x;
    else
      miniSum += num;
  }
  cout << miniSum << endl;
  return 0;
}
