n, m = list(map(int, input().split(' ')))

broken = [False] * (n + 1)
for i in range(m):
    broken[int(input())] = True

mod = 1_000_000_007

dp = [0] * (n + 1)
dp[0] = 1
dp[1] = 0 if broken[1] else 1

for i in range(2, n + 1):
    if broken[i]:
        dp[i] = 0
    else:
        c = dp[i - 1] + dp[i - 2]
        if c > mod:
            c = c % mod
        dp[i] = c

print(dp[n])
