import java.util.Scanner;

public class Main {
	public static void main(String[] args) throws Exception {
		Scanner sc = new Scanner(System.in);
		int d = sc.nextInt();
		int a = sc.nextInt();
		int b = sc.nextInt();
		sc.close();

		int ans = Integer.MAX_VALUE;
		for (int x = 0; x <= d; x++) {
			int c = x * a + (d - x) * b;
			ans = Math.min(ans, c);
		}
		System.out.println(ans);
	}
}