function a($)
    dim $b
    $ = split($,'/')
    $b = 0,0,3,0,1,0,1,0,0,1,0,1,0
    $a = ''+$[0]+'/'+$[1]+'/'+ (31-$b[$[1]] + ($[0] mod 4=)*(($[0] mod 400=)+($[0] mod 100>))*(2=$[1]))
endfunction