get "libhdr"

manifest $( limit = 1000 $)

let mertens(v, max) be
$(  v!1 := 1
    for n = 2 to max do
    $(  v!n := 1
        for k = 2 to n do
            v!n := v!n - v!(n/k)
    $)
$)

let start() be
$(  let m = vec limit
    let eqz, crossz = 0, 0

    writes("The first 99 Mertens numbers are:*N")
    mertens(m, limit)
    for y=0 to 90 by 10 do
    $(  for x=0 to 9 do
            test x+y=0
                then writes("   ")
                else writed(m!(x+y),3)
        wrch('*N')
    $)

    for x=2 to limit do
        if m!x=0 then
        $(  eqz := eqz + 1
            unless m!(x-1)=0 do crossz := crossz + 1
        $)

    writef("M(N) is zero %N times.*N", eqz)
    writef("M(N) crosses zero %N times.*N", crossz)
$)