n,m = map(int,input().split())
broken = [True] * (n+1)
for _ in range(m):
    broken[int(input())] = False

mod = 10 ** 9 + 7

dp = [0] * (n+1)
dp[-1] = 1
if broken[n-1]:
    dp[n-1] = 1

for i in reversed(range(n-1)):
    if broken[i]:
        dp[i] = dp[i+1] + dp[i+2] % mod
        
print(dp[0])