#include <bits/stdc++.h>
using namespace std;
int main() {
  long long int tests;
  tests = 1;
  while (tests--) {
    long long int a[4], i;
    for (long long int i = 0; i < 4; i++) {
      cin >> a[i];
    }
    sort(a, a + 4);
    if (a[0] + a[3] == a[1] + a[2] || a[3] == a[0] + a[1] + a[2]) {
      cout << "YES";
    } else {
      cout << "NO";
    }
  }
}
