r = 10 ** 9 + 7
N, M = map(int, input().split())
a = [int(input()) for _ in range(M)]
dp = [0] * (N+1)
a = sorted(set(a))

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

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

if N == 1 or N == 2:
    print(dp[N])
    exit()

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

print(dp[N])