#include <bits/stdc++.h>
using namespace std;
template <typename T>
void prn(T first) {
  cout << first << "\n";
}
int main() {
  int a[4];
  cin >> a[0] >> a[1] >> a[2] >> a[3];
  sort(a, a + 4);
  if (a[0] + a[3] == a[1] + a[2] || a[3] == a[0] + a[1] + a[2]) {
    cout << "YES";
  } else {
    cout << "NO";
  }
  return 0;
}
