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