Shell programming - Number - positive negative or zero

# Shell Programming 
# Positive negative or zero

echo -n "Hello "; logname
echo -n "enter a number : "
read a
if [ $a -lt 0 ]
then
echo " $a is negetive"
elif [ $a -gt 0 ]
then
echo "$a is Positive"
else
echo "$a is Zero"
fi