#include <iostream> #include <algorithm> #include <string> #include <vector> #include <cmath> #include <map> #include <queue> #include <iomanip> #include <set> #include <tuple> #define mkp make_pair #define mkt make_tuple #define rep(i,n) for(int i = 0; i < (n); ++i) using namespace std; typedef long long ll; const ll MOD=1e9+7; template<class T> void chmin(T &a,const T &b){if(a>b) a=b;} template<class T> void chmax(T &a,const T &b){if(a<b) a=b;} int main(){ cin.tie(0); ios::sync_with_stdio(false); vector<int> A(4); rep(i,4) cin>>A[i]; sort(A.begin(),A.end()); for(int i=1;i<4;i++){ if(A[0]+i!=A[i]){ cout<<"No"<<endl; return 0; } } cout<<"Yes"<<endl; return 0; }