n, m = map(int, input().split())
p = 1000000007
dp = [0] * n
c = 0
for _ in range(m):
    a = int(input())
    dp[a - 1] = -1
for i in range(1, n):
    if i <= 1:
        if dp[0] != -1 and dp[1] != -1:
            dp[0], dp[1] = 1, 2
        elif dp[0] == -1 and dp[1] != -1:
            dp[0], dp[1] = 0, 1
        elif dp[0] != -1 and dp[1] == -1:
            dp[0], dp[1] = 1, 0
        else:
            c = -1
    if i >= 2 and dp[i] != -1:
        if dp[i - 1] == -1 and dp[i - 2] != -1:
            dp[i] = dp[i - 2]
        elif dp[i - 1] != -1 and dp[i - 2] == -1:
            dp[i] = dp[i - 1]
        elif dp[i - 1] != -1 and dp[i - 2] != -1:
            dp[i] = (dp[i - 1] + dp[i - 2]) % p
        else:
            c = -1
if c == -1:
    print(0)
else:
    print(dp[n - 1])