#include <bits/stdc++.h>
using namespace std;
int n, a[6];
void solve() {
  for (int i = 1; i <= 4; i++) {
    cin >> a[i];
  }
  for (int m = 0; m < (1 << 4); m++) {
    int s1 = 0, s2 = 0;
    for (int i = 1; i <= 4; i++) {
      if (m & (1 << i)) {
        s1 += a[i];
      } else
        s2 += a[i];
    }
    if (s1 == s2) {
      cout << "YES\n";
      return;
    }
  }
  cout << "NO\n";
}
int main() {
  ios::sync_with_stdio(0);
  cin.tie(0), cout.tie(0);
  int tt = 1;
  while (tt--) {
    solve();
  }
  return 0;
}
