#include <bits/stdc++.h>
using namespace std;
long long gcd(long long a, long long b) {
  if (b == 0) return a;
  return gcd(b, a % b);
}
int main() {
  int second = 0, ss = 0, i, a[4], j;
  cin >> a[0] >> a[1] >> a[2] >> a[3];
  second = a[0] + a[1] + a[2] + a[3];
  if (second % 2) {
    cout << "NO";
    return 0;
  }
  sort(a, a + 4);
  for (i = 0; i < (1 << 4); i++) {
    ss = 0;
    for (j = 0; j < 4; j++) {
      if (i & (1 << j)) ss += a[j];
    }
    if (ss == (second / 2)) {
      cout << "YES";
      return 0;
    }
  }
  cout << "NO";
}
