PLAYER = 1
COMP   = 0

sum = 0
total = 0
turn = int(rand + 0.5)
dim precomp = {1, 1, 3, 2}

while sum < 21
    turn = 1 - turn
    print "The sum is "; sum
    if turn = PLAYER then
        print "It is your turn."
        while total < 1 or total > 3 or total + sum > 21
            input "How many would you like to total? ", total
        end while
    else
        print "It is the computer's turn."
        total = precomp[sum mod 4]
        print "The computer totals ", total, "."
    end if
    print
    sum += total
    total = 0
end while

if turn = PLAYER then
    print "Congratulations. You win."
else
    print "Bad luck. The computer wins."
end if