<?php
 
$n = 0;
$i=0;
$maxi=0;
$maxn=0;
 
for($i=1;$i<=100000000;$i++){
	collatz($i);
//	print $i." : ".$n."<br>";
 
	if ($maxn < $n){
		$maxi = $i;
		$maxn = $n;
	}
//print "change<br>";
 
	$n = 0;
	}
print "max : ".$maxi." (".$maxn.")";
return 0;
 
 
function collatz($num){
	if($num == 1){
//		print "".$GLOBALS['n'];
		return 0;
	}elseif($num%2==0){
		$num = $num /2;
		$GLOBALS['n']++;
//		print $num."\n";
		collatz($num);
	}else{
		$num = $num*3 +1;
//		print $num."\n";
		$GLOBALS['n']++;
		collatz($num);
	}
}
 
?>

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