quick blackjack script based off of TIY homework

blackjack.py

card_values = {
    'a' : 11,
    'k' : 10,
    'q' : 10,
    'j' : 10,
    '10' : 10,
    '9' : 9,
    '8' : 8,
    '7' : 7,
    '6' : 6,
    '5' : 5,
    '4' : 4,
    '3' : 3,
    '2' : 2
}

strategy_chart = {
    17 : {k : 'stand' for k in range(2, 12)},
    16 : {k : ('stand' if k < 7 else 'hit') for k in range(2, 12)},
    15 : {k : ('stand' if k < 7 else 'hit') for k in range(2, 12)},
    14 : {k : ('stand' if k < 7 else 'hit') for k in range(2, 12)},
    13 : {k : ('stand' if k < 7 else 'hit') for k in range(2, 12)},
    12 : {k : ('stand' if k < 7 and k > 3 else 'hit') for k in range(2, 12)},
    11 : {k : 'double down' for k in range(2, 12)},
    10 : {k : ('double down' if k < 10 else 'hit') for k in range(2, 12)},
    9 : {k : ('double down' if k < 7 else 'hit') for k in range(2, 12)},
    8 : {k : ('double down' if k < 7 and k > 4 else 'hit') for k in range(2, 12)},
    7 : {k : 'hit' for k in range(2, 12)},
    6 : {k : 'hit' for k in range(2, 12)},
    5 : {k : 'hit' for k in range(2, 12)},
}

first_card = input("What is your first card?\n> ")
first_value = card_values.get(first_card.lower(), None)
if first_value is None:
    print("that's not a card, nice try. Try: %s" % sorted(card_values.keys()))
    exit()

second_card = input("What is your second card?\n> ")
second_value = card_values.get(second_card.lower(), None)
if second_card is None:
    print("that's not a card, nice try. Try: %s" % sorted(card_values.keys()))
    exit()

dealer_card = input("What is the dealer's card?\n> ")
dealer_value = card_values.get(dealer_card.lower(), None)
if second_card is None:
    print("that's not a card, nice try. Try: %s" % sorted(card_values.keys()))
    exit()

print("You should... %s" % strategy_chart[first_value + second_value][dealer_value])