#include <bits/stdc++.h>
using namespace std;
int _I() {
  int x;
  scanf("%d", &x);
  return x;
}
struct node {
  int a, c;
  node(){};
  node(const int x, const int y) {
    a = x;
    c = y;
  }
  bool operator<(const node &R) const { return c < R.c; }
};
void solve() {
  int n = _I();
  int k = _I();
  int x = _I();
  int sum = 0;
  for (int i = 1; i <= n; i++) {
    int p = _I();
    if (i <= n - k)
      sum += p;
    else
      sum += x;
  }
  printf("%d\n", sum);
}
int main() {
  solve();
  return 0;
}
