N,M,*a=map(int,open(0).read().split())
dp=[0]*(N+1)
dp[0]=1
for i in a:
    dp[i]=0
if 1 in a:
    dp[1]=0
else:
    dp[1]=1
for i in range(2,N+1):
    if i not in a:
        dp[i]=dp[i-1]+dp[i-2]
print(dp[-1]%1000000007)    
