#include <bits/stdc++.h>
int main() {
  int a, b, c, d, p = 0;
  scanf("%d%d%d%d", &a, &b, &c, &d);
  if ((a + b) == (c + d))
    p++;
  else {
    if ((a + c) == (b + d))
      p++;
    else {
      if ((a + d) == (b + c))
        p++;
      else {
        if ((a + b + c) == d)
          p++;
        else {
          if ((a + c + d) == b)
            p++;
          else {
            if ((a + b + d) == c)
              p++;
            else {
              if ((b + c + d) == a) p++;
            }
          }
        }
      }
    }
  }
  if (p == 0)
    printf("NO\n");
  else
    printf("YES\n");
  return 0;
}
