N, M = map(int, input().split())

a = []

for i in range(M):
    a.append(int(input()))

    # 隣接してる場合は、0出力で終了
    if a[i] == a[i - 1] + 1:
        print(0)
        exit(0)

dp = [0] * (N + 1)

dp[0] = 1

if 1 in a:
    dp[1] = 0
else:
    dp[1] = 1

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

print(dp[-1] % 1000000007)


