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

public class Main {
	public static void main(String[] args) {
	
		int [] Y = new int[3]; 

		Scanner scanner= new Scanner(System.in);
		
	
		for(int i=0;i<Y.length;i++) {
			Y[i]=scanner.nextInt();
		}
			
	
		 Arrays.sort(Y);
		
	
		for(int i=0 ; i<Y.length-1 ; i++ ) {
			if(Y[i+1]-Y[i] !=1) {
				System.out.println("No");
				return;
			}
		}
		System.out.println("Yes");
	}
}