N, M = map(int, input().split())
dp = [0] * N
for _ in range(M):
    a = int(input())
    dp[a-1] = -1

k = 1000000007


for i in range(N):
    if dp[i] == -1:
        dp[i] = 0
        continue
    if i == 0:
        dp[i] = 1
        continue
    if i == 1:
        dp[i] = dp[i-1] + 1
        continue

    dp[i] = dp[i-1] + dp[i-2]
    dp[i] %= k



print(n)
