#include <bits/stdc++.h>
using namespace std;
const int MOD = 1000000007;
long double PI = 4 * atan(1);
int a[4];
int main() {
  ios::sync_with_stdio(0), cin.tie(0);
  for (int i = 0; i < 4; i++) cin >> a[i];
  sort(a, a + 4);
  if (a[3] == (a[0] + a[1] + a[2])) {
    cout << "YES";
  } else if ((a[3] + a[0]) == (a[1] + a[2])) {
    cout << "YES";
  } else if ((a[0] + a[1]) == (a[2] + a[3])) {
    cout << "YES";
  } else {
    cout << "NO";
  }
  return 0;
}
