N,M=map(int,input().split())
a=[]
for i in range(M):
   a.append(int(input()))
dp=[0]*(N+1)
dp[0]=1
if 1 not in a:
    dp[1]=1
for i in range(2,N+1):
    if i in a:
        continue
    dp[i]=(dp[i-1]+dp[i-2])
print(dp[-1]%1000000007)    