public int getNumber(int M, int[] L, int[] R) {
		boolean[] d = new boolean[M + 1];
		int count = 0;
		for (int i = L.length - 1; i >= 0; i--) {
			boolean isHit = false;
			for (int j = L[i]; j <= R[i]; j++) {
				if (!d[j]) {
					isHit = true;
					d[j] = true;
				}
			}
			if (!isHit) {
				count++;
			}
		}
		return 1 << (L.length - count);
	}