n:{.:x@&~(x<"0")|x>"9"} +/n'm:{(1_-6#-1_x)~5#!=v@>{(+/x=*x),-*x}'v,\:v:-7_x^"-01234567890"}#0:"day04" / 361724 / thanks to John Earnest +/n'm:{(1_-6#-1_x)~5#>#:'=v@