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