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