#include <bits/stdc++.h>
using namespace std;
long long n, k, x;
long long a[1000];
long long ans;
int main() {
  cin >> n >> k >> x;
  for (int i = 1; i <= n - k; ++i) {
    cin >> a[i];
    ans += a[i];
  }
  for (int i = n - k + 1; i <= n; ++i) {
    cin >> a[i];
  }
  ans += k * x;
  cout << ans << endl;
  return 0;
}
