N, M = map(int, input().split())
a = [int(input()) for _ in range(M)]
mod = 1000000007
dp = [0]*(N+1)
dp[0] = 1
for i in range(1, N+1):
    if i not in a:
        if i == 1:
            dp[i] = dp[i-1]
        else:
            dp[i] = (dp[i-1]+dp[i-2])%mod
print (dp[N])