#include <bits/stdc++.h>
using namespace std;
int main() {
  int a[4];
  cin >> a[0] >> a[1] >> a[2] >> a[3];
  sort(a, a + 4);
  int sum = a[0] + a[1] + a[2] + a[3];
  int cursum = a[3];
  if ((sum - cursum) == cursum) {
    cout << "YES";
    return 0;
  }
  cursum += a[0];
  if ((sum - cursum) == cursum) {
    cout << "YES";
    return 0;
  }
  cout << "NO";
}
