from collections import deque
N, M = map(int, input().split())
A = list(int(input()) for _ in range(M))
A = deque(A)
P = 10**9 + 7

dp = [0] * (N+1)
dp[0] = 1
dp[1] = 1
a = -1
if len(A):
    a = A.popleft()
    if 1 == a:
        dp[1] = 0
        a = A.popleft()

for i in range(2, N+1):
    if i != a:
        dp[i] = (dp[i-1] + dp[i-2]) % P
    else:
        dp[i] = 0
        if len(A):
            a = A.popleft()
print(dp[N])