public int getSum(int start, int end) {
		if (this.start == start && this.end == end)
			return sumVal;
		int mid = (this.start + this.end) / 2;
		if (start <= mid && end <= mid)
			return left.getSum(start, end);
		if (start > mid && end > mid)
			return right.getSum(start, end);
		return left.getSum(start, mid) + right.getSum(mid + 1, end);
	}