import java.io.*;
import java.util.*;


public class Main_yukicoder555_1 {

	private static Scanner sc;
	private static Printer pr;

	private static void solve() {
		final int INF = Integer.MAX_VALUE;

		int n = sc.nextInt();
		int c = sc.nextInt();
		int v = sc.nextInt();

		int[] dp = new int[n];
		Arrays.fill(dp, INF);
		dp[0] = 0;

		for (int i = 1; i < n; i++) {
			for (int j = 1; true; j++) {
				int next = i + i * j;
				next = Math.min(next, n);
				int cost = c + j * v;

				dp[next - 1] = Math.min(dp[next - 1], dp[i - 1] + cost);
				if (next == n) {
					break;
				}
			}
		}

		pr.println(dp[n - 1]);
	}

	// ---------------------------------------------------
	public static void main(String[] args) {
		sc = new Scanner(System.in);
		pr = new Printer(System.out);

		solve();

		pr.close();
		sc.close();
	}

	private static class Printer extends PrintWriter {
		Printer(PrintStream out) {
			super(out);
		}
	}
}