
n,m=map(int,input().split())
a=[True]*n
for i in range(m):
    a[int(input())]=False

mod=10**9+7
dp=[0]*(n+1)
dp[0]=1
if a[1]:
    dp[1]=1
else:
    dp[1]=0
for nn in range(2,n):
    if a[nn]:
        dp[nn]=(dp[nn-1]+dp[nn-2])%mod
    else:
        dp[nn]=0
if n>=2:
    dp[n]=(dp[n-1]+dp[n-2])%mod

print(dp[n])
