#include <bits/stdc++.h>
using namespace std;
int main() {
  int a, b, c, d, n;
  double m;
  scanf("%d%d%d%d", &a, &b, &c, &d);
  n = max(max(a, b), max(c, d));
  m = a + b + c + d;
  puts((m / 2 == (min(min(a, b), min(c, d)) + n) || n == m - n) ? "YES" : "NO");
  return 0;
}
