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