Certainly! Below is a test case generator for the "Speed" problem which you can use to generate valid inputs for the problem statement:

```python
import random

def generate_card():
    suits = ['S', 'H', 'D', 'C']
    ranks = ['A', 'K', 'Q', 'J', 'X'] + [str(i) for i in range(9, 1, -1)]
    return random.choice(suits) + random.choice(ranks)

def generate_deck(size):
    card_set = set()
    while len(card_set) < size:
        card_set.add(generate_card())
    return list(card_set)

def tcgen():
    test_cases = []
    
    for _ in range(random.randint(1, 10)):  # Generate up to 10 test cases
        NA = random.randint(1, 52)
        deck_A = generate_deck(NA)
        
        NB = random.randint(1, 52 - NA)
        deck_B = generate_deck(NB)
        
        test_cases.append((NA, deck_A, NB, deck_B))
    
    return test_cases

def format_test_cases(test_cases):
    formatted = []
    for NA, deck_A, NB, deck_B in test_cases:
        formatted.append(f"{NA}")
        formatted.append(" ".join(deck_A))
        formatted.append(f"{NB}")
        formatted.append(" ".join(deck_B))
    formatted.append("0")  # End of input indicator
    return "\n".join(formatted)

if __name__ == "__main__":
    test_cases = tcgen()
    formatted_test_cases = format_test_cases(test_cases)
    print(formatted_test_cases)
```

Explanation:
1. `generate_card()`: This function generates a random card by choosing a random suit and rank.
2. `generate_deck(size)`: This function generates a unique set of cards of given size.
3. `tcgen()`: This function generates multiple test cases, each containing decks for Robots A and B. It ensures that the total number of cards does not exceed 52.
4. `format_test_cases(test_cases)`: This function formats the test cases into the required input format for the problem.

You can run this script to generate input for the Speed problem. The formatted test cases will be printed to the console, ready for use in the competitive programming scenario.