function hail(integer n)
    if remainder(n,2)=0 then
        n /= 2
    else
        n = 3*n+1
    end if
    return n
end function

sequence hails = tagset(12),
         counts = repeat(0,12),
         results = columnize({hails})

function step(integer edx)
    integer n = hails[edx]
    if n=1 then return 0 end if
    n = hail(n)
    hails[edx] = n
    counts[edx] += 1
    results[edx] &= n
    return 1
end function

procedure main()
    bool done = false
    while not done do
        done = true
        for i=1 to 12 do
            if step(i) then
                done = false
            end if
        end for
    end while

    for i=1 to max(counts)+1 do
        for j=1 to 12 do
            puts(1,iff(i<=length(results[j])?sprintf("%4d",{results[j][i]}):"    "))
        end for
        puts(1,"\n")
    end for
    printf(1," %s\n",{join(repeat("===",12))})
    for j=1 to 12 do
        printf(1,"%4d",{counts[j]})
    end for
    puts(1,"\n")
end procedure

main()