#include <iostream>
using namespace std;

int main() {
	int ara[3][3] = {
		{1, 2, 3},
		{4, 5, 6},
		{7, 8, 9}
	};
	
	int a, b;
	cin >> a >> b;
	
	if((b-a)<=2)
		cout << "YES";
	else
		cout << "NO";
		
	return 0;
}