N,M = map(int,input().split())
A = [int(input()) for _ in range(M)]
mod = 1000000007
dp=[0]*(N+1)
dp[0]=1
if A[0]!=1:dp[1]=1 
else:dp[1]=0
    
for i in range(2,N+1):
    if i in A:
        dp[i]=0
    else:
        dp[i] = (dp[i-1]+dp[i-2])%mod

print(dp[N])