#include <bits/stdc++.h>
using namespace std;
const long long int mxn = 1e5 + 1;
string s;
char cs[1000][1000];
int main() {
  long long int n, m, i, z, j, a = 0, r = 1, ans = 0, k = 0, cnt = 0, b = 0;
  long long int c = 1, x, sm, q, l = 1, y, d = 0, sum = 0, mx = 0, mn = 0;
  string ss, strn;
  char ch;
  vector<long long int> vct;
  vector<long long int>::iterator vit;
  set<long long int> st;
  set<long long int>::iterator sit;
  long long int ara[1000];
  for (i = 0; i < 4; i++) {
    cin >> ara[i];
  }
  sort(ara, ara + 4);
  sum = 1;
  if (ara[0] + ara[3] == ara[1] + ara[2]) sum = 0;
  if (ara[0] + ara[1] + ara[2] == ara[3]) sum = 0;
  if (sum)
    cout << "NO" << endl;
  else
    cout << "YES" << endl;
  return 0;
}
