n, m = map(int, input().split())
a = []

for i in range(m):
    a.append(int(input()))

dp = [0] * (n+1)
dp[0] = 1
dp[1] = 1

for i in range(2, n+1):
    if i in a:
        dp[i] = 0
    else:
        dp[i] = (dp[i-1] + dp[i-2])%1000000007

print(dp[-1])