#include <bits/stdc++.h>
using namespace std;
int main() {
  int n[8];
  cin >> n[0] >> n[1] >> n[2] >> n[3];
  int k = 0;
  int s[6];
  for (int i = 0; i < 4; i++)
    for (int j = i + 1; j < 4; j++) {
      s[k] = n[i] + n[j];
      k++;
    }
  n[4] = n[1] + n[2] + n[3];
  n[5] = n[1] + n[2] + n[0];
  n[6] = n[0] + n[2] + n[3];
  n[7] = n[0] + n[1] + n[3];
  int flag = 0;
  for (int i = 0; i <= 2; i++)
    if (s[i] == s[6 - i - 1]) {
      cout << "YES";
      flag = 1;
      break;
    }
  if (flag == 0) {
    for (int j = 0; j < 4; j++)
      for (int k = 4; k < 8; k++)
        if (n[j] == n[k]) {
          cout << "YES";
          flag = 1;
          break;
        }
  }
  if (flag == 0) cout << "NO";
  return 0;
}
