n, m = map(int, input().split())
A = [int(input()) for i in range(m)]

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

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

print(dp[-1])
