#include <bits/stdc++.h>
using namespace std;
const long long M = 10007;
long long bigmod(long long p, long long q, long long m) {
  if (q == 0)
    return 1;
  else if (q % 2 == 1)
    return ((p % m) * (bigmod(p, q - 1, m) % m)) % m;
  else {
    long long c = bigmod(p, q / 2, m);
    return ((c % m) * (c % m)) % m;
  }
}
bool isprime(int n) {
  if (n == 2)
    return true;
  else if (n % 2 == 0)
    return false;
  for (int i = 3; i <= n; i += 2) {
    if (n % i == 0) return false;
  }
  return true;
}
int main() {
  int n, m;
  cin >> n >> m;
  if (n == 0 && m == 0)
    cout << "NO\n";
  else if (abs(n - m) > 1)
    cout << "NO\n";
  else
    cout << "YES\n";
  return 0;
}
