class Main {
  public static void main(String[] args){
    var sc = new java.util.Scanner(System.in);
    int d = sc.nextInt();
    int a = sc.nextInt();
    int b = sc.nextInt();
    int ans = (int) 1e9 + 7;
    for(int x = 0 ; x <= d ; x++)
      ans = Math.min(ans, x * a + (d - x) * b);
    System.out.println(ans);
  }
}