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

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



dp = [0] * (N + 1)


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] % 1000000007)