n,m=map(int,input().split()) 
a=[int(input()) for i in range(m)] 
dp=[0]*(n+1) 
if n==1: 
    print(1) 
else: 
    if 1 not in a: 
        dp[1]=1 
    if 2 not in a: 
        dp[2]=dp[1]+1 
    for i in range(3,n+1): 
        if i not in a: 
            dp[i]=dp[i-1]+dp[i-2] 
    print(dp[-1]%1000000007)