N,M = list(map(int,input().split()))
a = []
for _ in range(M):
    a.append(int(input()))
dp = [0] * (N + 1)
dp[0] = 1
dp[1] = 1
for i in range(2,N + 1):
    p = i-1 not in a
    q = i-2 not in a
    if p:
        dp[i] += dp[i-1]
        dp[i] %= 1000000007
    if q:
        dp[i] += dp[i-2]
        dp[i] %= 1000000007
print(dp[N])