#include <bits/stdc++.h>
using namespace std;
int main() {
  int a[4], f1, f2;
  for (int i = 0; i < 4; i++) {
    cin >> a[i];
  }
  sort(a, a + 4);
  for (int i = 0; i < 4; i++) {
    if ((a[1] + a[2] + a[3] + a[0]) / 2 == a[i] &&
        (a[1] + a[2] + a[3] + a[0]) % 2 == 0) {
      cout << "YES";
      return 0;
    }
  }
  if (a[0] + a[3] == a[1] + a[2])
    cout << "YES";
  else
    cout << "NO";
}
