n,m = map(int,input().split())
ls = [int(input()) for _ in range(m)]
dp = [0]*(n+1)
dp[0]=1
if 1 in ls:
    dp[1]= 0
else:
    dp[1]= 1
for i in range(2,n+1):
    if i in ls :
        continue
    else:
        dp[i] = dp[i-1]+dp[i-2]
print(dp[n]%(10**9+7))