N,M=map(int,input().split())
a=[]
for i in range(0,M):
    a.append(int(input()))
if M==0:
    a=[-1]
ans=1
s=[-1]*(N+1)
s[0]=1
def dp(n):
    if n==0:
        return 1
    elif n==1:
        return 0 if 1 in a else 1
    if s[n-1]!=-1:
        c=s[n-1]
    elif n-1 in a:
        s[n-1]=0
        c=0
    else:
        c=dp(n-1)%1000000007
        s[n-1]=c
    if s[n-2]!=-1:
        b=s[n-2]
    elif n-2 in a:
        s[n-2]=0
        b=0
    else:
        b=dp(n-2)%1000000007
        s[n-2]=b
    return (c+b)%1000000007
print(dp(N)%1000000007)