#include <bits/stdc++.h>
using namespace std;
const long long int MOD = 1e9 + 9;
const long long int maxn = 2e5 + 1;
long long int a[4];
void solve() {
  cin >> a[0] >> a[1] >> a[2] >> a[3];
  long long int sm = a[0] + a[1] + a[2] + a[3];
  for (int i = 0; i < 4; i++) {
    if (sm - a[i] == a[i]) {
      cout << "YES" << endl;
      return;
    }
  }
  for (int i = 0; i < 4; i++) {
    for (int j = 0; j < 4; j++) {
      if (i != j) {
        if (sm - a[i] - a[j] == a[i] + a[j]) {
          cout << "YES" << endl;
          return;
        }
      }
    }
  }
  cout << "NO" << endl;
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  long long int t = 1;
  while (t--) solve();
  return 0;
}
