#!/bin/sh
set -eu

usage() {
	cat <<-'EOF'
		Usage:
		  max NUMBER...
		  max -h
	EOF
}

help() {
	cat <<-'EOF'

		Options:
		  -h, --help    show this message

		Get the maximum number from the given values.
	EOF
}

for flag in "$@"; do
	case "$flag" in
		--)
			break
			;;
		--help)
			usage
			help
			exit
			;;
		*)
			;;
	esac
done

while getopts 'h' flag; do
	case "$flag" in
		h)
			usage
			help
			exit
			;;
		*)
			usage >&2
			exit 2
			;;
	esac
done
shift $((OPTIND - 1))

if [ -z "${1:-}" ]; then
	echo 0
	exit
fi

N="$1"
for n in "$@"; do
	N=$((N > n ? N : n))
done
echo "$N"