Two groups of 5 people are crossing a river in opposite directions by hopping on rocks. There are eleven rocks (numbered 1 - 11) and in the starting configuration, the empty rock is in between the two groups:

	 >   >   >   >   >       <   <   <   <   < 
	___ ___ ___ ___ ___ ___ ___ ___ ___ ___ ___
	 1   2   3   4   5   6   7   8   9   10  11

GOAL:

The objective is for the two groups to exchange sides, that is, to pass each other. Thus, the winning configuration is:

	 <   <   <   <   <       >   >   >   >   > 
	___ ___ ___ ___ ___ ___ ___ ___ ___ ___ ___
	 1   2   3   4   5   6   7   8   9   10  11

RULES:

1. You can only move forward in the direction you are facing. No backstepping or turning around.

2. Only one person may move at a time.

3. There are two kinds of legal moves:

• You may move into an adjacent empty space immediately in front of you.
• You may move around a person (or leapfrog over them) into an empty space behind them, if they are adjacent and FACING you.

EXAMPLES:

	    
	 >   >   >       >   <   >   <   <   <   < 
	___ ___ ___ ___ ___ ___ ___ ___ ___ ___ ___
	 1   2   3   4   5   6   7   8   9   10  11

	 >   >   >   >   <       >   <   <   <   < 
	___ ___ ___ ___ ___ ___ ___ ___ ___ ___ ___
	 1   2   3   4   5   6   7   8   9   10  11
	

	
	 >   >   >   >   <   <   <   <   <       > 
	___ ___ ___ ___ ___ ___ ___ ___ ___ ___ ___
	 1   2   3   4   5   6   7   8   9   10  11