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

a = [int(input()) for i in range(M)]


for i in range(M - 1):
    if a[i] + 1 == a[i+1]:
        print(0)
        exit()

dp = [0] * (N + 1)

if N == 1 and M != 1:
    print(1)
elif N == 1 and M == 1:
    print(0)

if 1 in a and 2 in a:
    print(0)
    exit()

if 1 in a:
    dp[1] = 0
    dp[2] = 1
elif 2 in a:
    dp[1] = 1
    dp[2] = 0
else:
    dp[1] = 1
    dp[2] = 2

for i in range(3,N+1):
    if i in a:
        dp[i] = 0
    else:
        dp[i] = (dp[i - 1] + dp[i - 2]) % 1000000007

print(dp[N])