n, m = map(int, input().split())
mod = 1000000007
a = [int(input()) for _ in range(m)]

dp = [0]*(n+1)
dp[0] = 1
if 1 not in a:
    dp[1] = 1

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

print(dp[n]%mod)