N,M = map(int,input().split())
A = [int(input()) for _ in range(M)]
dp = [0 for _ 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]
print(dp[N]%(10**9+7))
