#include <bits/stdc++.h>
using namespace std;
const long long INF = 1e18;
const long double inf = 1e18;
const long long MOD = (long long)(1e9 + 7);
const double EPS = 1e-6;
void file_io(string inp = "input.txt", string out = "output.txt",
             bool debug = false) {
  freopen(inp.c_str(), "r", stdin);
  if (!debug) freopen(out.c_str(), "w", stdout);
}
void fast_io() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);
}
int32_t main() {
  vector<long long> a(4, 0);
  for (long long i = 0; i < 4; ++i) cin >> a[i];
  for (long long i = 0; i < pow(2, 4); ++i) {
    long long sum = 0;
    for (long long j = 0; j < 4; ++j) {
      if ((i >> j) % 2)
        sum += a[j];
      else
        sum -= a[j];
    }
    if (sum == 0) {
      cout << "YES\n";
      return 0;
    }
  }
  cout << "NO\n";
  return 0;
}
