#include <bits/stdc++.h>
using namespace std;
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  int a, b, c, d, count = 0;
  cin >> a >> b >> c >> d;
  if ((a + b + c + d) % 2 == 0) {
    if (a + b == c + d) count++;
    if (a + c == b + d) count++;
    if (a + d == b + c) count++;
    if (a + b + c == d) count++;
    if (b + c + d == a) count++;
    if (a + c + d == b) count++;
    if (a + b + d == c) count++;
  }
  if (count)
    cout << "YES" << endl;
  else
    cout << "NO" << endl;
}
