#include <bits/stdc++.h>
long long gcd(long long a, long long b) { return b == 0 ? a : gcd(b, a % b); }
long long countDivisor(long long n) {
  long long divisor = 0;
  for (long long i = 1; i * i <= n; i++) {
    if (i * i == n)
      divisor += 1;
    else if (n % i == 0)
      divisor += 2;
  }
  return divisor;
}
int bmod(int a, int b, int m) {
  if (b == 0) return 1;
  int x = bmod(a, b / 2, m);
  x = (x * x) % m;
  if (b % 2 == 1) x = (x * a) % m;
  return x;
}
long long powr(long long n, long long m) {
  long long ans = 1;
  for (long long i = 1; i <= m; i++) ans *= n;
  return ans;
}
bool prime(long long n) {
  for (long long i = 2; i * i <= n; i++) {
    if (n % i == 0) return false;
  }
  return true;
}
int f1[3] = {+0, +1, +2};
using namespace std;
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  ;
  long long a, b;
  cin >> a >> b;
  if (a == 0 && b == 0) {
    cout << "NO";
    return 0;
  }
  if (abs(a - b) > 1)
    cout << "NO";
  else
    cout << "YES";
}
