#include <bits/stdc++.h>
using namespace std;
const int N = 1e6 + 1;
int s, m, res, n, a[N];
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  for (int i = 1; i <= 4; i++) {
    cin >> a[i];
  }
  sort(a + 1, a + 1 + 4);
  if (a[1] + a[4] == a[2] + a[3] || a[1] + a[2] + a[3] == a[4])
    cout << "YES";
  else
    cout << "NO";
  return 0;
}
