int x1 =1;
int x2 =2;
int x3 = 1;
active proctype process1 ()
{	
do
  x1 = (x3+1) % 4;
od	
	 
}

active proctype process2 ()
{	
do
 x2 = x1;
od	
}


active proctype process3 ()
{	
do
	x3 = x2;
od
}