N, M = map(int, input().split())
A = [int(input()) for _ in range(M)]
j = 0
dp = [0] * 100100
dp[0] = 1
for i in range(1,N+1):
    if i == A[j]:
        j += 1
        dp[i] = 0
    else:
        dp[i] = dp[i-1] + dp[i-2]
        dp[i] %= 10**9+7
print(dp[N])