#include <bits/stdc++.h>
using namespace std;
int main() {
  int arr[4];
  int sum = 0;
  for (int i = 0; i < 4; i++) {
    cin >> arr[i];
  }
  if (arr[0] + arr[1] == arr[2] + arr[3] ||
      arr[1] + arr[2] == arr[0] + arr[3] || arr[1] + arr[3] == arr[2] + arr[0])
    cout << "YES";
  else if (arr[0] + arr[1] + arr[2] == arr[3] ||
           arr[3] + arr[1] + arr[2] == arr[0] ||
           arr[0] + arr[3] + arr[2] == arr[1] ||
           arr[0] + arr[1] + arr[3] == arr[2])
    cout << "YES";
  else
    cout << "NO";
}
