Default password for admin user in Sitecore

I have installed Sitecore 7.2 on windows 7 and able to launch the sitecore site after the installation, but I was asked to login with username and password. There is no link for registration and I have no where provided the login details during the installation.

After checking the aspnetUsers and aspnetMembership database tables in the Core database, I have found that there is an admin user created by default. So what is the default password for this admin user? Thanks in advance.