#include <bits/stdc++.h>
using namespace std;
const long double E = 2.71828182845904523536;
const long double pi = acos(-1);
const double eps = 1e-9;
const long long mod = 1e9 + 7;
const long long inf = 1LL << 30;
const int N = 100100;
int a[N];
int main() {
  int n, k, x;
  scanf("%d%d%d", &n, &k, &x);
  for (int i = 0; i < n; i++) scanf("%d", &a[i]);
  int ans = 0;
  for (int i = 0; i < n - k; i++) ans += a[i];
  ans += k * x;
  printf("%d", ans);
  return 0;
}
