#include <bits/stdc++.h>
using namespace std;
bool is_vowel(char x) {
  if (x == 'a' or x == 'e' or x == 'i' or x == 'o' or x == 'u') return true;
  if (x == 'A' or x == 'E' or x == 'I' or x == 'O' or x == 'U') return true;
  if (x == 'y' or x == 'Y') return true;
  return false;
}
bool is_palindrome(string s) {
  int len = s.length();
  int n = len - 1;
  for (int i = 0; i < len; ++i, --n) {
    if (s[i] != s[n]) return false;
  }
  return true;
}
string to_str(long long x) {
  string ans = "";
  while (x != 0) {
    int d = x % 10;
    char c = (int)d + 48;
    ans.push_back(c);
    x = x / 10;
  }
  reverse(ans.begin(), ans.end());
  return ans;
}
bool is_prime(long long x) {
  if (x == 1 or x == 0) return false;
  if (x == 2) return true;
  for (long long i = 2; i * i <= x; ++i) {
    if (x % i == 0) return false;
  }
  return true;
}
int car_todig(char x) { return x - 48; }
char dig_tocar(int x) { return x + 48; }
bool is_upper(char x) {
  if (x >= 'A' and x <= 'Z')
    return true;
  else
    return false;
}
bool is_lower(char x) {
  if (x >= 'a' and x <= 'z')
    return true;
  else
    return false;
}
bool is_digit(char x) {
  if (x >= '0' and x <= '9')
    return true;
  else
    return false;
}
void solve() {
  int n, k, x;
  int ans = 0;
  cin >> n >> k >> x;
  ans = k * x;
  for (int i = 1; i <= n - k; ++i) {
    int d;
    cin >> d;
    ans += d;
  }
  cout << ans << endl;
}
int main() {
  ios::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);
  int t = 1;
  while (t--) {
    solve();
  }
  return 0;
}
