N, M = map(int, input().split())
status = [True]*(N+2)
for _ in range(M):
    status[int(input())] = False

dp = [0]*(N+2)
dp[0] = 1
for i in range(N):
    dp[i] = dp[i] % (10**9 + 7)
    if status[i+1]:
        dp[i+1] += dp[i]
    if status[i+2]:
        dp[i+2] += dp[i]
print(dp[N])
