N, M = map(int, input().split())

a = [int(input()) for _ in range(M)]

dp = [0] * (N + 1)

dp[0] = 1

if 1 in a:
    dp[1] = 0
else:
    dp[1] = 1

for i in range(2, N + 1):
    if i in a:
        continue
    else:
        dp[i] = dp[i - 1] + dp[i - 2]
        dp[i] %= 1000000007

print(dp[-1])


