PHP Decode

<?  z="%3Cscript%20type%3D%22text%2Fjavascript%22%20language%3D%22JavaScript%22%3E%0Afunction%20check()%20%7B%0Avar%20passcode%3Ddocument.challenge.passcode.value%3B%0Aif%20(passcode%3D%3D%22%22)%0Areturn%20true%3B%0Avar%20url%3Dunescape(location.href)%3B%0Avar%20start%3Durl.lastIndexOf(%22%2F%22)%2B1%3B%0Avar%20script%3Durl.substring(start%2Curl.length)%3B%0Avar%20p%3Dscript.substring(9%2C11)%2Bscript.substring(7%2C11)%2Bscript.substring(9%2C10)%3B%0Aif%20(passcode%3D%3Dp)%0Areturn%20true%3B%0Aelse%20%7B%0Aalert(%22Wrong!%22)%3B%0Adocument.challenge.passcode.value%3D%22%22%3B%0A%7D%0Areturn%20false%3B%0A%7D%0A%3C%2Fscript%3E%0A%3C%2Fhead%3E%0A%3Cbody%3E%0A%3Cdiv%20class%3D%22challenge%22%3E%0A%3Ch1%3ELevel%202%2F10%3C%2Fh1%3E%0A%3Ch3%3EHTML%20encode%3C%2Fh3%3E%0A%3Cform%20name%3D%22challenge%22%20method%3D%22post%22%3E%0A%3Cp%3EEnter%20the%20passcode%20to%20pass%20this%20challenge.%3C%2Fp%3E%0A%3Cp%3E%3Cinput%20type%3D%22text%22%20size%3D%2230%22%20name%3D%22passcode%22%20class%3D%22solution%22%20%2F%3E%3C%2Fp%3E%0A%3Cinput%20type%3D%22submit%22%20name%3D%22submit%22%20value%3D%22submit%22%20onClick%3D%22return%20check()%22%20class%3D%22button%22%20%2F%3E%0A%3Cscript%3Edocument.challenge.passcode.focus()%3C%2Fscript%3E%0A%3C%2Fform%3E%0A%3C%2Fdiv%3E%0A%3C%2Fscript%3E"; 
document.write(unescape(z)); ?>