N,M=map(int,input().split())
a=[0]*M
for i in range(M):
    a[i]=int(input())
MOD = 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):
    #n-1段目が安全なら
    if i-1 not in a:
        dp[i]+=dp[i-1]
    #n-2段目が安全なら
    if i-2 not in a:
        dp[i]+=dp[i-2]
    dp[i] = dp[i]%MOD
print(dp[N])