#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using db = double;
int mod = 1000000007;
db pie = 3.1415926535;
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  int a[4];
  int i;
  int s = 0;
  for (i = 0; i < 4; i++) {
    cin >> a[i];
    s += a[i];
  }
  int j;
  bool flag = false;
  for (i = 0; i < 4; i++) {
    for (j = i + 1; j < 4; j++) {
      int d = a[i] + a[j];
      if (s - d == d) {
        flag = true;
        break;
      }
    }
  }
  if (flag) {
    cout << "YES"
         << "\n";
    return 0;
  }
  for (i = 0; i < 4; i++) {
    if (s - a[i] == a[i]) {
      flag = true;
      break;
    }
  }
  if (flag) {
    cout << "YES"
         << "\n";
  } else
    cout << "NO"
         << "\n";
}
