code: private void del(int k)
  	{
  		//if(last < 0)    last = sapp[-1] -= (k);
  		//else            last = *sapp++ = -(k);
  
  		if(last < 0)    last = sapp[sappPos-1]   -=  (k);
  		else            last = sapp[(sappPos++)]  = -(k);
  	}
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