n, m = map(int, input().split())
a = [int(input()) for _ in range(m)]

dp = [0] * (n + 10)
dp[0] = 1
mod = 1e9 + 7

ok = [1] * (n + 10)
for i in a:
    ok[i] = 0

for i in range(n):
    if ok[i + 1]:
        dp[i + 1] += dp[i]
        dp[i + 1] %= mod
    if ok[i + 2]:
        dp[i + 2] += dp[i]
        dp[i + 2] %= mod
print(dp[n])
