n,m=map(int,input().split())
a=[]
for i in range(m):
  a_=int(input())
  a.append(a_)
  
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
    continue
  dp[i]=dp[i-1]+dp[i-2]
#print(dp)
print(dp[n]%(1000000007))