%!PS

% begin included library code
% see https://codeberg.org/Firedrake/postscript-libraries/
/strjoin % [(a) (b) (c)] (j) -> (ajbjc)
{
    3 dict begin
    /j exch def
    dup 0 get /out exch def
    /first true def
    {
        first {
            pop
            /first false def
        } {
            out j strconcat
            exch strconcat
            /out exch def
        } ifelse
    } forall
    out
    end
} bind def

/test.start {
    print (:) print
    /test.pass 0 def
    /test.count 0 def
} bind def

/alloccvs {
    2 dict begin
    /n exch def
    /a 1 def
    n
    dup 0 lt {
        /a a 1 add def
        neg
    } if
    {
        dup 10 lt {
            exit
        } if
        /a a 1 add def
        10 idiv
    } loop
    pop
    n a string cvs
    end
} bind def

/s2a {
    [ exch { } forall ]
} bind def


/enumerate.array {
    1 dict begin
    /a exch def
    [
      0 1 a length 1 sub {
          [ exch dup a exch get ]
      } for
    ]
    end
} bind def

/test.end {
    ( ) print
    test.count 0 gt {
        (Passed ) print
        test.pass (...) cvs print
        (/) print
        test.count (...) cvs print
        ( \() print
        test.pass 100 mul test.count idiv (...) cvs print
        (%\)) print
        (\r\n) print
    } if
} bind def

/a2s {
    2 dict begin
    /i exch def
    i length dup string /o exch def
    1 sub 0 exch 1 exch {
        dup i 3 -1 roll get o 3 1 roll put
    } for
    o
    end
} bind def

/test {
    /test.count test.count 1 add def
    {
        /test.pass test.pass 1 add def
    } {
        ( ) print
        test.count (....) cvs print
        (-fail) print
    } ifelse
} bind def

/strconcat % (a) (b) -> (ab)  
{
    [
        3 -1 roll
        s2a aload length
        2 add -1 roll
        s2a aload pop
    ] a2s
} bind def


% end included library code

/groupdigitsum {
    0 dict begin
    /sz exch def
    /s exch s2a def
    /n 0 def
    {
        [
            s enumerate.array {
                aload pop
                /c exch def
                /i exch def
                /n n c add 48 sub def
                i s length 1 sub eq
                i 1 add sz mod 0 eq or {
                    n alloccvs
                    /n 0 def
                } if
            } forall
        ] () strjoin /s exch def
        s length sz le {
            exit
        } if
    } loop
    s
    end
} bind def

(groupdigitsum) test.start
(111122333) 3 groupdigitsum (359) eq test
(1222312) 2 groupdigitsum (76) eq test
(100012121001) 4 groupdigitsum (162) eq test
test.end