#include <bits/stdc++.h>
using namespace std;
int a[5];
int total;
void solve(int idx, int sum) {
  if (idx == 4) {
    if (sum * 2 == total) {
      cout << "YES";
      exit(0);
    }
    return;
  }
  solve(idx + 1, sum + a[idx]);
  solve(idx + 1, sum);
}
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  for (int i = 0; i < 4; i++) {
    cin >> a[i];
    total += a[i];
  }
  solve(0, 0);
  cout << "NO";
  return 0;
}
