import java.util.Arrays;
import java.util.Scanner;

public class Main {
	final long MODULO = 1_000_000_000 + 7;

	void run() {
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		int c = sc.nextInt();
		int v = sc.nextInt();
		int[] dp = new int[2 * n - 2 + 1];
		Arrays.fill(dp, Integer.MAX_VALUE / 16);
		dp[1] = 0;
		for (int i = 1; i < dp.length; ++i) {
			for (int j = i * 2; j < dp.length; j += i) {
				dp[j] = Math.min(dp[j], dp[i] + (j / i - 1) * v + c);
			}
		}
		long ans = Long.MAX_VALUE / 16;
		for (int i = n; i < dp.length; ++i) {
			ans = Math.min(ans, dp[i]);
		}
		System.out.println(ans);
	}

	static void tr(Object... objects) {
		System.out.println(Arrays.deepToString(objects));
	}

	public static void main(String[] args) {
		new Main().run();
	}
}