n, m = map(int, input().split())
a = [int(input()) for _ in range(m)]
mod = int(1e9 + 7)
notbroken = [True for _ in range(n+1)]

for i in a:
  notbroken[i] = False

dp = [0 for _ in range(n+1)]
dp[0] = 1
dp[1] = 1
for i in range(2, n+1):
    if not i in a:
        dp[i] += dp[i-1] + dp[i-2]
        dp[i] %= mod

print(dp[n])