#include <bits/stdc++.h>
using namespace std;
const int maxn = 1010;
int a[maxn];
int main() {
  int n = 4;
  for (int i = 0; i < n; i++) {
    cin >> a[i];
  }
  sort(a, a + n);
  int sum, ans;
  sum = ans = 0;
  ans = a[3];
  int l = 0;
  n = 2;
  while (n >= 0) {
    if (ans > sum)
      sum += a[n--];
    else {
      ans += a[n--];
    }
  }
  if (ans == sum)
    cout << "YES" << endl;
  else
    cout << "NO" << endl;
  return 0;
}
