#include <bits/stdc++.h>
using namespace std;
int A[4];
int main() {
  cin >> A[0] >> A[1] >> A[2] >> A[3];
  int all_summ = A[0] + A[1] + A[2] + A[3];
  for (int mask = 0; mask < (1 << 4); mask++) {
    int summ = 0;
    for (int i = 0; i < 4; i++) summ += (mask & (1 << i)) ? A[i] : 0;
    if (summ == all_summ - summ) {
      cout << "YES" << endl;
      return 0;
    }
  }
  cout << "NO" << endl;
}
