
N, M = map(int, input().split(" "))
AL = list(map(int, [input() for _ in range(M)]))

# DP
dp = [0] * (N + 1)
dp[0] = 1
dp[1] = 1 if 1 not in AL else 0
divisor = 10 ** 9 + 7

for i in range(2, N + 1):
    if i in AL:
        continue
    dp[i] = (dp[i-1] + dp[i-2]) % divisor
print(dp[N])