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