#include <bits/stdc++.h>
using namespace std;
int main() {
  int i, j, k, n, m, a, b, c, d;
  cin >> a >> b >> c >> d;
  k = a + b + c + d;
  if (k % 2 != 0)
    cout << "NO";
  else {
    i = k;
    k /= 2;
    if (k - a - b == 0 && k - c - d == 0)
      cout << "YES";
    else if (k - a - c == 0 && k - b - d == 0)
      cout << "YES";
    else if (k - a - d == 0 && k - c - b == 0)
      cout << "YES";
    else if (a == k)
      cout << "YES";
    else if (b == k)
      cout << "YES";
    else if (c == k)
      cout << "YES";
    else if (d == k)
      cout << "YES";
    else
      cout << "NO";
  }
}
