#include <bits/stdc++.h>
using namespace std;
const double eps = 1e-10;
const double Pi = 3.1415926535897932;
const int dir[4][2] = {-1, 0, 0, -1, 1, 0, 0, 1};
const int maxn = 100 + 5;
int a[maxn];
int main() {
  int n = 0;
  for (int i = 1; i <= 4; i++) {
    scanf("%d", &a[i]);
    n += a[i];
  }
  bool ok = false;
  for (int i = 1; i <= n; i++)
    if (a[i] * 2 == n) ok = true;
  for (int i = 1; i <= 4; i++) {
    for (int j = i + 1; j <= 4; j++) {
      if ((a[i] + a[j]) * 2 == n) ok = true;
    }
  }
  puts(ok ? "YES" : "NO");
  return 0;
}
