n,m=map(int,input().split())
dp=[0]*(n+3)
for i in range(m):
    dp[int(input())]=-1

for i in range(1,n+1):
    if dp[i]==-1:
        continue 
    else:
        if dp[i-1]!=-1:
            dp[i]+=dp[i-1]
        if dp[i-2]!=-1:
            dp[i]+=dp[i-2]

print(dp[n]%1000000007)