n,m = map(int,input().split())
a = [int(input()) for i in range(m)]
mod = 10**9+7
dp = [0]*n
dp[0] = 1
dp[1] = 2
for i in range(2,n):
    if i+1 in a:
        dp[i] = 0
    else:
        dp[i] = (dp[i-1] + dp[i-2])%mod
print(dp[n-1])