#include <bits/stdc++.h>
using namespace std;
void solve() {
  int a[4];
  cin >> a[0] >> a[1] >> a[2] >> a[3];
  int sum = a[0] + a[1] + a[2] + a[3];
  if (sum % 2 == 1) {
    cout << "NO";
    return;
  }
  sum = sum / 2;
  if (a[0] == sum || a[1] == sum || a[2] == sum || a[3] == sum ||
      a[0] + a[1] == sum || a[0] + a[2] == sum || a[0] + a[3] == sum ||
      a[1] + a[2] == sum || a[1] + a[3] == sum || a[2] + a[3] == sum)
    cout << "YES";
  else
    cout << "NO";
}
int main() {
  int T;
  T = 1;
  while (T--) solve();
  return 0;
}
