n, m = map(int, input().split())

# a = set()
# for i in range(m):
#     a_tmp = int(input())
#     a.add(a_tmp)

a = [int(input()) for i in range(m)]

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