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