/ -:\|=2 thanks to Jack Andrews

,/$.[3 3#1+!9]'1+'((-1|1&+)/(,/-:\|=2)"RDLU"?)',\0:"day02"
/ 56983

m:{$[2<+/{%x*x}x+y; x; x+y]}
m:{$[4<+/u*u:x+y;x;u]}
,/.[5 5#"zz1zzz234z56789zABCzzzD"]'2+'(m/(,/-:\|=2)"RDLU"?)',\0:"day02"
/ 8B8B1

\\