from collections import deque
N, M = map(int, input().split())
A = deque()
[A.append(int(input())) for _ in range(M)]

dp = [0]*(N+3)
dp[0] = 1

for i in range(N+1):
    if A:
        a = A[0]
    if len(A) >= 2:
        b = A[1]

    dp[i] = dp[i] % (10**9 + 7)
    if not i+1 == a:
        dp[i+1] += dp[i]
    else:
        A.popleft()
    if not i+2 == b and not i+2 == a:
        dp[i+2] += dp[i]
print(dp[N])
