#include <bits/stdc++.h>
using namespace std;

const int MAXN = 50000;

int N;
int C, V;

int dp[MAXN * 2];

int main() {
  ios::sync_with_stdio(false);
  cin >> N;
  cin >> C >> V;
  memset(dp, 0x3f, sizeof(dp));
  dp[1] = 0;
  for (int i = 1; i < N; ++i) {
    for (int j = 2; j * i < N * 2; ++j) {
      dp[j * i] = min(dp[j * i], dp[i] + C + V * (j - 1));
    }
  }
  cout << *min_element(dp + N, dp + N * 2) << endl;
  return 0;
}