MOD = 1e9 + 7

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

dp = [0] * (n+1)
dp[0] = 1
for i in range(1, n+1):
    if i in a:
        continue
    if i > 1:
        dp[i] = (dp[i-1] + dp[i-2]) % MOD
    else:
        dp[i] = dp[i-1]

print(int(dp[n]))
