N,M = map(int,input().split())
A = tuple([int(input()) for _ in range(M)])
mod = 1000000007
dp=[0]*(N+1)
dp[0]=1
if M != 0:
    if A[0]!=1:
        dp[1]=1 
    else:
        dp[1]=0
else:
    dp[1]=1
    
for i in range(2,N+1):
    if i in A:
        dp[i]=0
    else:
        dp[i] = (dp[i-1]+dp[i-2])%mod

print(dp[-1])