n, m = list(map(int, input().split()))
a = [int(input()) for _ 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:
    dp[i] = 0
  else:
    dp[i] = dp[i-1] + dp[i-2]
  
print(dp[n]%1000000007)