N, M = map(int, input().split())
A = [int(input()) for _ in range(M)]
mod = 10**9 +7
dp = [0]*(N+1)
dp[0] = 1
if len(A)>=1 and N>=1:
    if A[0]==1:
        dp[1]=0
    else:
        dp[1]=1
for i in range(2, N+1):
    if i not in A:
        dp[i] = (dp[i-1]+dp[i-2])%mod
print(dp[-1])