#include <bits/stdc++.h>
using namespace std;
template <class T>
T maxx(T A, T B) {
  return (A > B) ? A : B;
}
template <class T>
T minn(T A, T B) {
  return (A < B) ? A : B;
}
bool sortinrev(const pair<int, int> &a, const pair<int, int> &b) {
  return (a.first > b.first);
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);
  long long int tt, n, m, k, i, j, l, a, b, c, d;
  long long int sx = 0, sy = 0, sz = 0;
  tt = 1;
  while (tt--) {
    cin >> a >> b >> c >> d;
    if ((a + b == c + d) || (a + c == b + d) || (a + d == b + c) ||
        (a + b + c == d) || (a + c + d == b) || (b + c + d == a) ||
        (a + b + d == c))
      cout << "YES\n";
    else
      cout << "NO\n";
  }
  return 0;
}
