#include <bits/stdc++.h>
using namespace std;
bool check(int a, int b, int c, int d) {
  if (a + b == c + d) return 1;
  if (a + c == b + d) return 1;
  if (a + d == b + c) return 1;
  if (a == b + c + d) return 1;
  if (b == a + c + d) return 1;
  if (c == a + b + d) return 1;
  if (d == a + b + c) return 1;
  return 0;
}
int main() {
  ios::sync_with_stdio(0);
  int a, b, c, d;
  cin >> a >> b >> c >> d;
  if (check(a, b, c, d)) {
    cout << "YES";
  } else {
    cout << "NO";
  }
  return 0;
}
