#include <bits/stdc++.h>
using namespace std;
bool f = 0;
int a[4];
void dfs(int dep, int sum1, int sum2) {
  if (dep == 4) {
    f |= (sum1 == sum2);
    return;
  }
  dfs(dep + 1, sum1 + a[dep], sum2);
  dfs(dep + 1, sum1, sum2 + a[dep]);
}
int main() {
  ios::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);
  cin >> a[0] >> a[1] >> a[2] >> a[3];
  if ((a[0] + a[1] + a[2] + a[3]) & 1) {
    puts("NO");
    return 0;
  }
  dfs(0, 0, 0);
  puts(f ? "YES" : "NO");
  return 0;
}
