#include <iostream>
#include <algorithm>
#include <vector>
#include <string>

using namespace std;

long long n, c, v;

int f(int k) {
  if (k >= n) return 0;
  long long ret = 1e18;
  for (int i = 1;; i++) {
    ret = min(ret, f(k + k * i) + v * i);
    if (k + k * i >= n) break;
  }
  return ret + c;
}

int main() {
  cin >> n >> c >> v;
  cout << f(1) << endl;
}