#include <bits/stdc++.h>
using namespace std;
int n, k, x, a;
int main() {
  scanf("%d%d%d", &n, &k, &x);
  int sum = k * x;
  for (int i = k; i < n; i++) scanf("%d", &a), sum += a;
  printf("%d\n", sum);
  return 0;
}
