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