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

public class Main {
	
	public static long MOD = 1000000007;
	
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		
		final int N = sc.nextInt();
		final int C = sc.nextInt();
		final int V = sc.nextInt();
		
		long[] min_cost = new long[2 * N + 1];
		Arrays.fill(min_cost, Long.MAX_VALUE / 2 - 1);
		min_cost[1] = 0;
		
		for(int i = 1; i <= N; i++){
			for(int j = 2 * i, count = 1; j <= 2 * N; j += i, count++){
				final long paste_cost = C + count * V;
				min_cost[j] = Math.min(min_cost[j], min_cost[i] + paste_cost);
			}
		}
		
		long min = Long.MAX_VALUE / 2 - 1;
		for(int i = N; i <= 2 * N; i++){
			min = Math.min(min, min_cost[i]);
		}
		//System.out.println(Arrays.toString(min_cost));
		System.out.println(min);
	}
}