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