#include <bits/stdc++.h>
using namespace std;
using i64 = long long;
#define rep(i,s,e) for(i64 (i) = (s);(i) < (e);(i)++)
#define all(x) x.begin(),x.end()

template<class T>
static inline std::vector<T> ndvec(size_t&& n, T val) noexcept {
  return std::vector<T>(n, std::forward<T>(val));
}

template<class... Tail>
static inline auto ndvec(size_t&& n, Tail&&... tail) noexcept {
  return std::vector<decltype(ndvec(std::forward<Tail>(tail)...))>(n, ndvec(std::forward<Tail>(tail)...));
}

int main() {
  vector<i64> v(4);
  rep(i,0,4) cin >> v[i];
  sort(all(v));
  bool OK = true;
  rep(i,1,4) {
    if(v[i] == v[0] + i) {

    }
    else {
      OK = false;
    }
  }
  if(OK) {
    cout << "Yes" << endl;
  }
  else {
    cout << "No" << endl;
  }
}