#c dp version
n,m = map(int,input().split())
a=[]
for i in range(m):
    a.append(int(input()) )
from collections import deque
a=deque(a)
mod=10**9 + 7

dp=[0]*(n+2)
dp[0]=0
dp[1]=1
aa=a.popleft()
for i in range(2,n+2):
    if i-1 == aa:
        dp[i]=0
        if len(a)>0:
            aa=a.popleft()
    else:
        dp[i]=( dp[i-1]+dp[i-2] )%mod
print(dp[-1])