N,M=map(int,input().split())
a=[int(input()) for i in range(M)]
dp=[0]*(N+1)
dp[0]=1
dp[1]=0 if 1 in a else 1
mod=10**9+7

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

print(dp[N])