#include <bits/stdc++.h>
using namespace std;
int read() {
  int x = 0;
  char c;
  for (c = getchar(); !isdigit(c); c = getchar())
    ;
  for (; isdigit(c); c = getchar()) x = (x << 3) + (x << 1) + (c ^ 48);
  return x;
}
int a[4];
int main() {
  a[0] = read(), a[1] = read(), a[2] = read(), a[3] = read();
  sort(a, a + 4);
  cout << (a[0] + a[3] == a[1] + a[2] || a[0] + a[1] + a[2] == a[3] ? "YES"
                                                                    : "NO");
}
