#include <bits/stdc++.h>
using namespace std;
signed main() {
  long long int a[4];
  for (long long int i = 0; i < 4; i++) cin >> a[i];
  sort(a, a + 4);
  long long int s = 0;
  for (long long int i = 0; i < 4; i++) s += a[i];
  long long int f = 0;
  for (long long int i = 0; i < 4; i++) {
    for (long long int j = 0; j < 4; j++) {
      if (i != j) {
        long long int x = a[i] + a[j];
        if (x == s - x) f = 1;
      }
    }
  }
  long long int b = a[1] + a[2] + a[3];
  long long int c = a[0] + a[2] + a[3];
  long long int d = a[0] + a[1] + a[3];
  long long int e = a[0] + a[1] + a[2];
  if (b == s - b) f = 1;
  if (c == s - c) f = 1;
  if (d == s - d) f = 1;
  if (e == s - e) f = 1;
  if (f)
    cout << "YES";
  else
    cout << "NO";
}
