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