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

a = [int(input()) for i in range(M)]
dp = [0] * (N + 1)
dp[0] = 0
if 1 in a:
    dp[1] = 0
    dp[2] = 1
else:
    if 2 in a:
        dp[1] = 1
        dp[2] = 0
    else:
        dp[1] = 1
        dp[2] = 2
for i in range(3,N+1):
    if i in a:
        dp[i] = 0
    else:
        dp[i] = (dp[i-1] + dp[i-2]) % 1000000007

print(dp[N])