#include <bits/stdc++.h>
using namespace std;
int main() {
  int a, b, c, d;
  cin >> a >> b >> c >> d;
  int sum = a + b + c + d;
  if (a + b == c + d || a + c == b + d || a + d == b + c || a == sum - a ||
      b == sum - b || c == sum - c || d == sum - d) {
    cout << "YES";
  } else {
    cout << "NO";
  }
  return 0;
}
