import random


def string_checker(question, valid_ans=("yes", "no")):
    error = f"Please enter a valid option from the following list: {valid_ans}"

    while True:
        user_response = input(question).strip().lower()

        if not user_response:
            print(error + "\n")
            continue

        for item in valid_ans:
            if user_response == item or user_response == item[0]:
                return item

        print(error + "\n")


def instruction():
    print("""
~~~ 𝐐𝐮𝐢𝐳 𝐈𝐧𝐬𝐭𝐫𝐮𝐜𝐭𝐢𝐨𝐧𝐬 ~~~

~~ How to Play:
- Select the total number of questions you want to play.
- A problem will appear on your screen each turn. Type your numeric answer and hit Enter.
- You'll immediately see if your response was right or wrong.
- Need to leave early? Type <xxx> at any prompt to quit the game instantly.

Good luck!
""")


# --- Main Program ---

score = 0
answer_check = ["yes", "no"]

# Check if user wants instructions
want_instruction = string_checker("Do you want to see the instructions? ", answer_check)
if want_instruction == "yes":
    instruction()

# Ask for rounds
rounds_input = input("\nHow many rounds would you like to play? ").strip().lower()

while not rounds_input.isdigit() or int(rounds_input) < 1:
    print("⚠️ Please enter a valid number greater than 0. ⚠️")
    rounds_input = input("How many rounds would you like to play? ").strip().lower()

total_rounds = int(rounds_input)
question_num = 1