N, M = map(int, input().split())
a = []
issafe = [True for _ in range(N)]
for i in range(M):
    a.append(int(input()))
    issafe[a[i]] = False

dp = [0 for _ in range(N+1)]
dp[0] = 1
if issafe[1]:
    dp[1] = 1

for i in range(2, N+1):
    if issafe[i-1]:
        dp[i] += dp[i-1]
    if issafe[i-2]:
        dp[i] += dp[i-2]
    dp[i] %= 1000000007

print(dp[N])