http://securityoverride.org

These hacking challenges are designed to put your hacking skills to the test. For each challenge completed you will receive points based on the level of the challenge. The Scoreboard will keep track of your points so you know where you rank among other SecurityOverride members. Your profile will also be updated as challenges are completed to include your total points and a list of the challenges you have successfully completed.

Try it, it's amazing.

If (you have problems) { send me messages on codeforces, I'll help you. } else good luck

:D