#include <bits/stdc++.h>
using namespace std;
signed main() {
  do {
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    cout.tie(NULL);
  } while (0);
  ;
  long long int a, b, c, d;
  cin >> a >> b >> c >> d;
  bool flag;
  if (a == b + c + d)
    flag = true;
  else if (b == a + c + d)
    flag = true;
  else if (c == a + b + d)
    flag = true;
  else if (d == a + c + b)
    flag = true;
  else {
    if (a + b == d + c)
      flag = true;
    else if (a + c == b + d)
      flag = true;
    else if (a + d == b + c)
      flag = true;
    else
      flag = false;
  }
  if (flag)
    cout << "YES";
  else
    cout << "NO";
  return 0;
}
