count unique ip addresses in unix hosts file

hi unix gurus!!!
im stumped on a simple solution for this.
for an/etc/hosts file that contains entries in format:
IPAddress <space> Hostname <newline>

Example: localhost webserver

what would be the simplest way to COUNT the number of UNIQUE IPAddresses in a single piped command?

J PAsked:
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joolsSenior Systems AdministratorCommented:
something like;
   cat /etc/hosts | awk '{print $1}' | sort -n | uniq | wc -l

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joolsSenior Systems AdministratorCommented:
or :-)
  cat /etc/hosts | grep -v "^#" | grep -v "^$" | awk '{print $1}' | sort -n | uniq | wc -l

 cat /etc/hosts | grep -v '^#' | awk '{ print $1 } ' | sort | uniq -c
J PAuthor Commented:
thanks you all for prompt help !!!
Or a shorter solution is

awk '/^[0-9]/ {print $1}' /etc/hosts | sort -u | wc -l
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