n, m = map(int, input().split())
hole_ids = [int(input()) - 1 for _ in range(m)]
X = 1000000007


def solve(n, hole_ids):
    # nums = []
    nums = [0] * n
    for i in range(n):
        if i in hole_ids:
            # nums.append(0)
            nums[i] = 0
            continue

        if i == 0:
            # nums.append(1)
            nums[i] = 1
        elif i == 1:
            # 1つ前から1段上がるから2つ前から2個飛ばし
            # nums.append(nums[-1] + 1)
            nums[i] = nums[i-1] + 1
        else:
            # nums.append((nums[-1] % X + nums[-2] % X) % X)
            nums[i] = (nums[i-1] + nums[i-2]) % X
    return nums[-1]


print(solve(n, hole_ids))
