<s>[INST] Given a positive integer N and a number K, find all prime factors of the difference N-K and N+K.
Use the code to calculate prime factors.


```python
def prime_factors(n):
    """Return a set of prime factors of n"""
    i = 2
    factors = set()
    while i * i <= n:
        if n % i:
            i += 1
        else:
            n //= i
            factors.add(i)
    if n > 1:
        factors.add(n)
    return factors


def find_prime_factors(N, K):
    """Find all prime factors of the difference N-K and N+K."""
    return prime_factors(N-K), prime_factors(N+K)


# Test the function
N = 100
K = 5
print(find_prime_factors(N, K))
```

However, the code may not work correctly when N-K or N+K is less than or equal to 0. What adjustments are needed to make the function work for these cases?[/INST]