n,m = map(int, input().split())
a = [int(input()) for _ in range(m)]

mod = 1000000007
dp = [0]*(n+1)
dp[0] = 1
if 1 not in a:
  dp[1] = 1
else:
  dp[1] = 0

for i in range(2, n+1):
  if i in a:
    continue
  dp[i] = dp[i-1] + dp[i-2]
  dp[i] %= mod
  
print(dp[n])