def xor_decrypt(ciphertext_bytes, key):
    return bytes(b ^ key for b in ciphertext_bytes)

def is_printable_ascii(data):
    try:
        decoded = data.decode('ascii')
        return all(32 <= c <= 126 for c in data)
    except Exception:
        return False

def find_flag(ciphertext_hex):
    ciphertext_bytes = bytes.fromhex(ciphertext_hex.replace('-', ''))
    
    for key in range(256):
        decrypted = xor_decrypt(ciphertext_bytes, key)
        
        if is_printable_ascii(decrypted):
            text = decrypted.decode('ascii')
            if 'flag{' in text:
                print(f"[+] Key found: {hex(key)}")
                print(f"Decrypted text: {text}")
                return text
    print("[-] No valid flag found.")
    return None

ciphertext = "5f-55-58-5e-42-71-7a-6d-7f-48-4e-5c-78-6a-7d-08-0e-0a-44"
find_flag(ciphertext)