n,m=map(int,input().split())
a = list(int(input()) for i in range(m))

INF=1000000007
dp=[0]*(n+1)
dp[0]=1
if 1 in a:
    dp[1]=0
else:
    dp[1]=1

for i in range(2,n+1):
    if i in a:
        continue
    dp[i]=dp[i-1]+dp[i-2]
    dp[i]%=INF

print(dp[n])