#include <bits/stdc++.h>
using namespace std;
int main() {
  int a[4], i, sum = 0, flag = 0;
  for (i = 0; i < 4; i++) {
    cin >> a[i];
    sum += a[i];
  }
  sort(a, a + 4);
  if (sum % 2)
    cout << "NO" << endl;
  else {
    sum /= 2;
    int temp = 0;
    int l = 0, h = 0;
    while (h < 4) {
      if (temp == sum) {
        break;
      }
      if (temp < sum)
        temp += a[h++];
      else {
        temp -= a[l++];
      }
    }
    if (temp == sum)
      cout << "YES" << endl;
    else {
      cout << "NO" << endl;
    }
  }
}
