#include <bits/stdc++.h>
using namespace std;
int main() {
  ios ::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  int a, b, c, d;
  cin >> a >> b >> c >> d;
  int x = a + b;
  int y = c + d;
  int z = a + c;
  int xx = b + d;
  int xy = a + d;
  int xz = b + c;
  if (x == y or z == xx or xy == xz or a + b + c == d or b + c + d == a or
      a + c + d == b or a + b + d == c)
    cout << "YES" << endl;
  else
    cout << "NO" << endl;
  return 0;
}
