n,m= map(int, input().split())
a = [int(input()) for _ in range(m)]
dp=[0]*(n+1)
dp[0]=1
j=0

for i in range(1,n+1):
    if i==a[j]:
        if j<m-1:
            j+=1
    else:
        if i==1:
            dp[i]=1
        else:
            dp[i]=dp[i-1]+dp[i-2]

print(dp[n]%(10**9+7))