#include <bits/stdc++.h>
using namespace std;
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);
  long long n, i, j, k = 0, l = 0, m = 0, a = 0, b = 0, c, sum = 0, x = 0,
                     y = 0, z;
  int arr[4];
  for (i = 0; i < 4; i++) {
    cin >> arr[i];
  }
  sort(arr, arr + 4);
  a = arr[2];
  b = arr[3];
  if (b + arr[0] == a + arr[1]) {
    cout << "YES";
    return 0;
  } else if (b == a + arr[0] + arr[1]) {
    cout << "YES";
    return 0;
  } else {
    cout << "NO";
  }
  return 0;
}
