N,M = map(int,input().split())
a = [int(input()) for i in range(M)]

dp = [0]*(N+1)
dp[0] = 1

if 1 in a:
    dp[1] = 0
else:
    dp[1] = 1

for i in range(2,N+1):
    if i in a:
        continue
    dp[i] = dp[i-2] + dp[i-1]

print(dp[N] % (10**9+7))
