n,m=map(int,input().split())
l=[]
for _ in range(m):
    l.append(int(input()))
#print(l)
dp=[0]*(n+1)
dp[0]=1
if l[0]!=1:dp[1]=1
for i in range(2,n+1):
    if i in l:
        dp[i]=0
    else:
        dp[i]=dp[i-1]+dp[i-2]
print(dp[-1]%1000000007)