#!/bin/bash
declare -A rooms
declare -a stack
let 'max=-1^1<<63'
input=${1:-input.txt}
while read -n1 c
do
	case $c in
	^)	rooms=() stack=() rooms[0 0]=0 x=0 y=0 dist=0 farthest=0 sp=-1 ;;
	\()	stack[++sp]="x=$x y=$y dist=$dist" ;;
	\|)	declare -i ${stack[sp]} ;;
	\))	declare -i ${stack[sp--]} ;;
	N)	let --y ;;&
	S)	let ++y ;;&
	E)	let ++x ;;&
	W)	let --x ;;&
	[NSEW]) if let "++dist < ${rooms[$x $y]:-$max}"
		then
			rooms[$x $y]=$dist
			let 'dist > farthest' && farthest=$dist
		fi ;;
	esac
done <"$input"
echo $farthest