n, m = map(int, input().split())
a = [int(input()) for i in range(m)]
mod = 10**9+7
dp = [0]*(n+1)
dp[0], dp[1] = 1, 1
if 1 in a:
    dp[1] = 0
for i in range(2, n+1):
    if i not in a:
        dp[i] = dp[i-1] + dp[i-2]
        dp[i] %= mod
print(dp[n])