#include <bits/stdc++.h>
int main() {
  int n = 4;
  int a[n];
  for (int i = 0; i < n; ++i) {
    std ::cin >> a[i];
  }
  std ::sort(a, a + n);
  std ::cout << ((a[0] + a[3] == a[1] + a[2]) || (a[0] + a[1] + a[2] == a[3])
                     ? "YES\n"
                     : "NO\n");
  return 0;
}
