#!/bin/sh -u
 
if test $# -ne 1
then
	echo "Usage: $0 <u0>"
	exit 1
fi

Un=$1
while test $Un -ne 1
do
 	if test `expr $Un % 2` -eq 0
 	then
 		Un=`expr $Un / 2`
 	else
 		Un=`expr ($Un * 3)+1`
 	fi
done