%!PS

% begin included library code
% see https://codeberg.org/Firedrake/postscript-libraries/
/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

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

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

/reverse {
    1 dict begin
    dup length /l exch def
    [ exch
      aload pop
      2 1 l {
          -1 roll
      } for
    ]
    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


% end included library code

/maximumpairs {
    0 dict begin
    /n 0 def
    /r 0 dict def
    {
        /s exch def
        /t s s2a reverse a2s def
        r t known {
            /n n 1 add def
        } {
            r s true put
        } ifelse
    } forall
    n
    end
} bind def

(maximumpairs) test.start
[(ab) (de) (ed) (bc)] maximumpairs 1 eq test
[(aa) (ba) (cd) (ed)] maximumpairs 0 eq test
[(uv) (qp) (st) (vu) (mn) (pq)] maximumpairs 2 eq test
test.end