INIT = 0
n, m = map(int, input().split())
a = [INIT for i in range(m)]
for i in range(m):
    a[i] = int(input())

dp = [INIT for i in range(n + 1)]
dp[0] = 1

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

print(dp[n] % 1000000007)
