n,m=map(int,input().split())
a = [int(input()) for i in range(m)]
dp=[0]*(n+1)
for i in range(n,-1,-1):
  if i not in a:
    if i==n or i==n-1:
      dp[i]=1
    else:
      dp[i]=dp[i+1]+dp[i+2]
print(dp[0]%1000000007)