# Typical Stairs

n, m = map(int, input().split())
a = []
MOD = 10**9 + 7
for i in range(m):
    a.append(int(input()))

if n == 1:
    print(1)
    exit()

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:
        dp[i] = 0
    else:
        dp[i] = (dp[i - 1] + dp[i - 2]) % MOD

print(dp[-1])
