while(1)
	{
		enemy_pan1.pos_x += speed_x;
		
		if (enemy_pan1.pos_x >= 500)
		{
			enemy_pan1.pos_x = 500;
			
			while(1)
			{
			enemy_pan1.pos_x -= speed_x;
			
			if (enemy_pan1.pos_x <= 300)
		   {
		   enemy_pan1.pos_x = 300;
			}
	      
	      wait(1);
			}
	
		}
			
		wait(1);
	}

while(1)
{
   enemy_pan1.pos_x += speed_x;
   if (enemy_pan1.pos_x >= 500)
   {
      enemy_pan1.pos_x = 500;
      while(enemy_pan1.pos_x > 300)
      {
         enemy_pan1.pos_x -= speed_x;
         wait(1);
      }
      enemy_pan1.pos_x = 300;
   }
   wait(1);
}

while(1)
{
	enemy_pan1.pos_x += speed_x;
	if((enemy_pan1.pos_x >= 500)||(enemy_pan1.pos_x <= 300))
	{	speed_x = -speed_x;	}
	wait(1);
}

while(1)
{
   enemy_pan1.pos_x = minv(enemy_pan1.pos_x + speed_x, 500);
   while(enemy_pan1.pos_x != 300)
   {
      enemy_pan1.pos_x = maxv(enemy_pan1.pos_x - speed_x, 300);
      wait(1);
   }
   wait(1);
}