#include <bits/stdc++.h>
using namespace std;
template <typename T>
T gcd(T a, T b) {
  return (b == 0) ? a : gcd(b, a % b);
}
template <typename T>
T lcm(T a, T b) {
  return a * (b / gcd(a, b));
}
template <typename T>
T mod_exp(T b, T p, T m) {
  T x = 1;
  while (p) {
    if (p & 1) x = (x * b) % m;
    b = (b * b) % m;
    p = p >> 1;
  }
  return x;
}
template <typename T>
T invFermat(T a, T p) {
  return mod_exp(a, p - 2, p);
}
template <typename T>
T exp(T b, T p) {
  T x = 1;
  while (p) {
    if (p & 1) x = (x * b);
    b = (b * b);
    p = p >> 1;
  }
  return x;
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  ;
  int a, b;
  cin >> a >> b;
  if (a == 0 && b == 0) {
    cout << "NO" << '\n';
  } else if (abs(a - b) <= 1)
    cout << "YES" << '\n';
  else
    cout << "NO" << '\n';
  return 0;
}
