#include <bits/stdc++.h>
using namespace std;
string solve(istream &stream) {
  int a, b;
  stream >> a >> b;
  if (abs(a - b) <= 1 && a + b > 0) {
    return "YES";
  } else {
    return "NO";
  }
  return "";
}
int main() {
  int a = 1;
  bool debug = false;
  if (debug) {
    ifstream infile;
    infile.open("input.txt");
    ofstream outfile;
    outfile.open("output.txt");
    while (!infile.eof()) {
      outfile << solve(infile) << endl;
    }
    infile.close();
    outfile.close();
  } else {
    cout << solve(cin) << endl;
  }
  return 0;
}
