import itertools
n, m = map(int, input().split())
a = [int(input()) for i in range(m)]
mod = 10 ** 9 + 7
dp = [0 for i in range(n + 1)]

dp[0] = 1

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

print(dp[n])
