$k = 25; 
$N = 10000;

while ($k>=2)
	{
	if ($k==1) 	
		{last;}
		$mean = (4*$N)/($k*($k-1));
		$time = (-log(rand)*$mean);
		
		push (@cls, $time);
		
		$k=$k-1;
		}
	open (GENE,'>coal.xls'); 
	for ($time=0; $time<24; $time ++) {
		print GENE "@cls[$time]\n";
		}