import java.util.Scanner;
public class Clever_Lily {
    public static void main(String[] args) {
        Scanner scanner = new Scanner( System.in );
        int age = Integer.parseInt( scanner.nextLine() );
        double wash = Double.parseDouble( scanner.nextLine() );
        int price = Integer.parseInt( scanner.nextLine() );
        int toys = 0;
        int cash = 0;
        int even = 0;

        for (int i = 1; i <= age; i++) {
            if ( i % 2 == 0) {
                cash += 5 * i;
                even++;
            } else {
                toys++;
            }
        }
        int c = cash + (toys * price) - even;
        if (c >= wash) System.out.printf( "Yes! %.2f", (double) (c - wash) );
        else System.out.printf( "No! %.2f", (double) (wash - c) );

    }
}