#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
#define pb push_back
#define fi first
#define se second
typedef pair<ll,ll> P;
using VP = vector<P>; using VVP = vector<VP>;
using VI = vector<ll>; using VVI = vector<VI>; using VVVI = vector<VVI>;
const int inf=1e9+7;
const ll INF=1LL<<61;
const ll mod=1e9+7;

template<class T>
inline bool chmax(T &a, T b) {
  if(a < b) {
    a = b;
    return true;
  }
  return false;
}

template<class T>
inline bool chmin(T &a, T b) {
  if(a > b) {
    a = b;
    return true;
  }
  return false;
}

int main(){
  int i,j;
  int v[4];
  for(i=0;i<4;i++) cin>>v[i];
  sort(v,v+4);
  if(v[1]==v[0]+1&&v[2]==v[0]+2&&v[3]==v[0]+3) cout<<"Yes"<<endl;
  else cout<<"No"<<endl;


}