%!PS

/apush { % [a b] c -> [a b c]
    /t exch def
    [ exch aload pop t ]
} bind def

/factorpairs {
    /nn exch def
    nn 1 eq {
        [ 2 ]
    } {
        /ff 0 array def
        /s nn sqrt cvi def
        s s mul nn eq {
            /ff ff s 2 mul apush def
            /s s 1 sub def
        } if
        2 1 s {
            /pf exch def
            nn pf mod 0 eq {
                /ff ff pf nn pf idiv add apush def
            } if
        } for
        /ff ff 1 nn add apush def
        ff
    } ifelse
} bind def

/is_stealthy {
    /n exch def
    /p n factorpairs def
    /stl false def
    p length 1 ne {
        0 1 p length 2 sub {
            /ix exch def
            ix 1 add 1 p length 1 sub {
                /iy exch def
                p ix get p iy get sub abs
                1 eq {
                    /stl true def
                    exit
                } if
            } for
            stl {
                exit
            } if
        } for
    } if
    stl
} bind def

36 is_stealthy true eq { (Pass) } { (FAIL) } ifelse print ( ) print
12 is_stealthy true eq { (Pass) } { (FAIL) } ifelse print ( ) print
6 is_stealthy false eq { (Pass) } { (FAIL) } ifelse =