N,M=map(int,input().split())
a=[int(input()) for i in range(M)]
dp=[1]*(N+1)
dp[0]=1
dp[1]=1

for i in range(1,N+1):
    if i in a:
        dp[i]=0
    elif i==1:
        pass
    else:
        dp[i]=(dp[i-1]+dp[i-2])%1000000007

print(dp[N])