text: #include "lib.h"
  
  void umain()
  {
  	int a = 0;
  	int id = 0;
  
  	if ((id = fork()) == 0)
  	{
  		if ((id = fork()) == 0)
  		{
  			a += 3;
  			for (;;)
  				writef("\t\tthis is child2 :a:%d\n", a);
  		}
  		a += 2;
  		for (;;)
  			writef("\tthis is child :a:%d\n", a);
  	}
  	a++;
  	for (;;)
  		writef("this is father: a:%d\n", a);
  }
  