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