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

using namespace std;

int main() {
  int n, c, v;
  cin >> n >> c >> v;

  vector<int> dp(n * 2 + 1, 1e9);

  dp[1] = 0;
  for (int i = 1; i < dp.size(); i++) {
    for (int j = i * 2; j < dp.size(); j += i) {
      dp[j] = min(dp[j], dp[i] + c + (j - i) / i * v);
    }
  }

  int ans = 1e9;
  for (int i = n; i < dp.size(); i++) {
    ans = min(ans, dp[i]);
  }
  cout << ans << endl;
}