from collections import deque

n,m=map(int,input().split())
step=list(range(2,n+1))
broken=[]
for i in range(m):
    broken+=[int(input())]
mod=10**9+7
dp=[0]*(n+1)
dp[0]=1
if m==0:
    dp[1]=1
elif not broken[0]==1:
    dp[1]=1
b=deque(broken)
if len(broken) != 0:
    bad_one = b.popleft()
else:
    bad_one = -1
for i in step:
    if i != bad_one:
        dp[i]=(dp[i-1]+dp[i-2])%mod
    elif i == bad_one and len(b) != 0:
        bad_one = b.popleft()
print(dp[n])