n, m = map(int, input().split())
a = [int(input()) for _ in range(m)]
dp = [0] * (n + 1)
dp[0] = 1 if 0 not in a else 0
dp[1] = 1 if 1 not in a else 0
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[n])
