public int pointToSymbol(int midCount) {
	int low = 0;
	int high = TOTAL_INDEX;
	while (true) { // binary search returns when it finds result
     	    int mid = (high+low)/2;
	    if (_count[mid] > midCount) { 
		if (high == mid) --high;
		else high = mid; 
	    } else if (_count[mid+1] > midCount) {
		return (mid==EOF_INDEX) ? EOF : mid;
	    } else { 
		if (low==mid) ++low;
		else low = mid;
	    }
	}
    }