n,m=map(int,input().split())
a=[int(input()) for i in range(m)]
dp=[0]*(n+1)
ans=0
if n-1 not in a:
    dp[1]=1
if n-2 not in a:
    dp[2]=dp[1]+1
for i in range(3,n+1):
    if n-i not in a:
        dp[i]=dp[i-1]+dp[i-2]
    else:
        continue
print(dp[n]%1000000007)