n, m = map(int, input().split())
list_score = set([int(input()) for _ in range(m)])

dp = [0] * (n + 1)
mod = pow(10, 9) + 7

dp[0] = 1
if list_score[0] == 1:
    dp[1] = 0
else:
    dp[1] = 1

for i in range(2, n + 1):
    if i in list_score:
        continue
    dp[i] = dp[i - 1] + dp[i - 2]
    dp[i] %= mod

print(dp[n])