#wire_1=(R98 U47 R26 D63 R33 U87 L62 D20 R33 U53 R51)
#wire_2=(U98 R91 D20 R16 D67 R40 U7 R15 U6 R7)
+filename=${1:-input.txt}
+
# read in data from file instead
-exec 3<input.txt
+exec 3<"$filename"
IFS="," read -u 3 -a wire_1
IFS="," read -u 3 -a wire_2