#include <bits/stdc++.h>
using namespace std;
const long long N = 2e5 + 30, Mod = 1e9 + 7;
const long long SQ = 330;
long long a[N];
int main() {
  ios::sync_with_stdio(0), cin.tie(0);
  for (int i = 0; i < 4; i++) cin >> a[i];
  string ans = "NO";
  for (int mask = 0; mask < 16; mask++) {
    long long s1 = 0, s2 = 0;
    for (int i = 0; i < 4; i++) {
      if (mask & (1 << i))
        s1 += a[i];
      else
        s2 += a[i];
    }
    if (s1 == s2) ans = "YES";
  }
  cout << ans;
  return (0);
}
