N,M = map(int,input().split())

a = [int(input()) for i in range(M)]

wa = (10**9) + 7

#dpを使う

dp = [0]*(N+1)
dp[0]=1
now_a = 0
if len(a)!=0:
    a.reverse()
    now_a = a.pop()
if len(a)==0:
    now_a = -1
for i in range(1,N+1):
    if i==1:
        dp[i]=dp[i-1]
    else:
        dp[i]=dp[i-1] + dp[i-2]
    if i == now_a:
        dp[i]=0
        if len(a)!=0:
            now_a = a.pop()
        else:
            now_a = -1

print(dp[N]%wa)



