#include <stdio.h>
#include <bits/stdc++.h>
using namespace std;
#define int long long int
#define IOS ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);
const int N = 3e5 + 7;
int32_t main(){
    IOS;
    int t;
    t=1;
    while(t--){
        int x,y;
        cin >> x >> y;
        int p = abs(x-y);
        if(p>=3) cout << "No" ;
        else cout << "Yes";
        
        cout << endl;
    }
    return 0;
}
#include<bits/stdc++.h>
using namespace std;
using ll = long long;
int main(){
  vector<int> a(4);
  for(int i=0;i<4;i++){
    cin>>a[i];
  }
  sort(a.begin(),a.end());
  cout<<a[0]<<endl;
  return 0;
}
