#include <bits/stdc++.h>
using namespace std;
long long int __xor(long long int a, long long int b) { return a ^ b; }
long long int __and(long long int a, long long int b) { return a & b; }
long long int __or(long long int a, long long int b) { return a | b; }
long long int ai[10000000], pi[10000000];
int main() {
  long long int b, c, x, y, z, t, i, j, k, l1, l2, m, n, c1 = 0, a[4];
  scanf("%lld", &a[0]);
  scanf("%lld", &a[1]);
  scanf("%lld", &a[2]);
  scanf("%lld", &a[3]);
  if (a[0] + a[1] == a[2] + a[3] || a[0] + a[2] == a[1] + a[3] ||
      a[0] + a[3] == a[1] + a[2] || a[0] + a[1] + a[2] == a[3] ||
      a[1] + a[2] + a[3] == a[0] || a[1] == a[0] + a[2] + a[3] ||
      a[2] == a[0] + a[1] + a[3])
    cout << "YES";
  else
    cout << "NO";
  return 0;
}
