134 btw: using right vs. substr is in this case equal in score .. 


function a($)
    $ = split($,'/')
    $a = $[0]+'/'+$[1]+'/'+(31-right(_1_1__1_1_3_,$[1])+($[0] mod 4=0 & ($[0] mod 400=0|$[0] mod 100>) & 2=$[1]))
endfunction
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