n,m=map(int,input().split())
a=[int(input()) for _ in range(m)]
if a[0]==0:
    print(0)
    exit()

dp=[0]*(n+1)
dp[0]=1

for i in range(1,n+1):
    if i in a:
        dp[i]=0
        continue

    dp[i]=dp[i-1]
    if i>1:dp[i]+=dp[i-2]
    dp[i]%=1000000007
print(dp[-1])