#include <bits/stdc++.h>
using namespace std;
int main() {
  int a, b, c, d, cnt = 0;
  cin >> a >> b >> c;
  vector<int> v;
  for (int i = 0; i < a; i++) {
    cin >> d;
    v.push_back(d);
  }
  for (int i = 0; i < v.size() - b; i++) {
    cnt += v[i];
  }
  cnt += b * c;
  cout << cnt;
}
