N, M = map(int, input().split())
#a = [0 for _ in range(N + 1)]
dp = [-1 for _ in range(N + 1)]
dp[0] = 1
for _ in range(M):
    a = int(input())
    dp[a] = 0
mod = 10**9 + 7

def f(n):
    if n < 0:
        return 0
    if dp[n] == -1:
        dp[n] = (f(n - 1) + f(n - 2)) % mod
    return dp[n]
print(f(N))
