n, m = map(int, input().split())
broken = [0] * (n + 1)

for i in range(m):
    a = int(input())
    broken[a] = 1

dp = [0] * (n + 1)
mod = 1000000007

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

print(dp[n])