#include <bits/stdc++.h>
using namespace std;
int main(int argc, char const *argv[]) {
  int bags[4];
  int flag = 0;
  for (int i = 0; i < 4; i++) {
    cin >> bags[i];
  }
  if (bags[0] + bags[1] == bags[2] + bags[3]) {
    cout << "YES\n";
  } else if (bags[0] + bags[2] == bags[1] + bags[3]) {
    cout << "YES\n";
  } else if (bags[0] + bags[3] == bags[1] + bags[2]) {
    cout << "YES\n";
  } else if (bags[0] + bags[1] + bags[2] == bags[3] ||
             bags[0] + bags[2] + bags[3] == bags[1] ||
             bags[0] + bags[1] + bags[3] == bags[2] ||
             bags[3] + bags[1] + bags[2] == bags[0]) {
    cout << "YES\n";
  } else {
    cout << "NO\n";
  }
  return 0;
}
