#include <bits/stdc++.h>
using namespace std;
int main() {
  int A[4], i, s = 0, t1, t2, t3;
  for (i = 0; i < 4; i++) {
    cin >> A[i];
    s += A[i];
  }
  t1 = A[0] + A[1];
  t2 = A[0] + A[2];
  t3 = A[0] + A[3];
  int h = s / 2;
  if (s % 2 != 0) {
    cout << "NO";
    exit(0);
  }
  for (i = 0; i < 4; i++) {
    if (A[i] == h) {
      cout << "YES";
      exit(0);
    }
  }
  if ((t1 == h) || (t2 == h) || (t3 == h)) {
    cout << "YES";
    exit(0);
  }
  cout << "NO";
  return 0;
}
