#include <bits/stdc++.h>
using namespace std;
int main() {
  int ara[4];
  cin >> ara[0] >> ara[1] >> ara[2] >> ara[3];
  sort(ara, ara + 4);
  if (ara[3] > ara[0] + ara[1] + ara[2]) {
    cout << "NO" << endl;
  } else if ((ara[3] == (ara[0] + ara[1] + ara[2])) ||
             (ara[3] + ara[0] == ara[2] + ara[1]) ||
             (ara[3] + ara[0] + ara[1] == ara[2])) {
    cout << "YES" << endl;
  } else {
    cout << "NO" << endl;
  }
  return 0;
}
