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