a, b = [int(i) for i in input().split()]
if a == 0 and b == 0:
print('NO')
else:
if abs(a-b) == 0 or abs(a-b) == 1:
print('YES')
else:
print('NO')#include <bits/stdc++.h>
using namespace std;
int main() {
int a, b;
cin >> a >> b;
if(abs(a - b) > 1 || (a == 0 && b == 0)) {
cout << "NO\n";
}
else {
cout << "YES\n";
}
}/*1687667841.014395*/337B - Routine Problem | 1392D - Omkar and Bed Wars |
76E - Points | 762C - Two strings |
802M - April Fools' Problem (easy) | 577B - Modulo Sum |
1555B - Two Tables | 1686A - Everything Everywhere All But One |
1469B - Red and Blue | 1257B - Magic Stick |
18C - Stripe | 1203B - Equal Rectangles |
1536A - Omkar and Bad Story | 1509A - Average Height |
1506C - Double-ended Strings | 340A - The Wall |
377A - Maze | 500A - New Year Transportation |
908D - New Year and Arbitrary Arrangement | 199A - Hexadecimal's theorem |
519C - A and B and Team Training | 631A - Interview |
961B - Lecture Sleep | 522A - Reposts |
1166D - Cute Sequences | 1176A - Divide it |
1527A - And Then There Were K | 1618E - Singers' Tour |
1560B - Who's Opposite | 182B - Vasya's Calendar |