#include <bits/stdc++.h>
using namespace std;
int main() {
  int a[4], sum = 0;
  for (int i = 0; i < 4; ++i) {
    cin >> a[i];
    sum += a[i];
  }
  bool flag = false;
  for (int i = 0; i < 4; ++i) {
    for (int j = 0; j < 4; ++j) {
      if (i == j) {
        int sum1 = a[i];
        int sum2 = sum - sum1;
        if (sum1 == sum2) {
          flag = true;
        }
        continue;
      }
      int sum1 = a[i] + a[j];
      int sum2 = sum - sum1;
      if (sum1 == sum2) {
        flag = true;
      }
    }
  }
  if (flag) {
    cout << "YES\n";
  } else {
    cout << "NO\n";
  }
  return 0;
}
