#include <bits/stdc++.h>
using namespace std;
long long in() {
  int32_t x;
  scanf("%d", &x);
  return x;
}
inline long long lin() {
  long long x;
  scanf("%lld", &x);
  return x;
}
inline void read(long long *a, long long n) {
  for (long long i = 0; i < n; i++) a[i] = in();
}
inline void readL(long long *a, long long n) {
  for (long long i = 0; i < n; i++) a[i] = lin();
}
const long long maxn = 2e6 + 10;
const long long mod = 1e9 + 7;
const long long MAX_VAL = 1e18 + 10;
const long long MAGIC = 350;
int32_t main() {
  long long n = in(), k = in(), x = in();
  long long rem = n - k;
  long long res = 0;
  for (long long i = 0; i < n; i++) {
    long long foo = in();
    if (i < rem)
      res += foo;
    else
      res += x;
  }
  cout << res << endl;
}
