#include <bits/stdc++.h>
using namespace std;
int main() {
  int a[4];
  for (int i = 0; i < 4; i++) {
    cin >> a[i];
  }
  sort(a, a + 4);
  bool is = false;
  if (a[0] + a[3] == a[1] + a[2]) {
    is = true;
  }
  if (a[0] + a[1] + a[2] == a[3]) {
    is = true;
  }
  if (is) {
    cout << "YES\n";
  } else {
    cout << "NO\n";
  }
  return 0;
}
