n,m=map(int,input().split())
a=[int(input()) for _ in range(m)]
dp=[0]*(n+1)
dp[0]=1
dp[1]=1
for i in range(1,n+1):
    if i in a:
        dp[i]=0
    elif i in a and i+1 in a:
        print(0)
        exit()
    else:
        dp[i]=dp[i-2]+dp[i-1]
print(dp[n]%1000000007)