n,m=map(int,input().split())
a=[int(input()) for _ in range(m)]
dp=[0]*(n+1)
for i in range(m):
    dp[n-a[i]]=-1
if dp[1]==0:
    dp[1]=1
else:
    dp[1]=0
if dp[2]==0:
    dp[2]=dp[1]+1
else:
    dp[2]=0
if n>=3:
    for i in range(3,n+1):
        if dp[i]==0:
            dp[i]=dp[i-1]+dp[i-2]
        else:
            dp[i]=0
print(dp[n]%1000000007)