n,m=map(int,input().split())
a=[]
for _ in range(m):
  a.append(int(input()))
if m==0:
  a=[-1]
dp=[0]*(n+1)
dp[0]=1
if 1 not in a:
  dp[1]=1
for i in range(2,n+1):
  if i-2 not in a and i-1 not in a:
     dp[i]=dp[i-2]+dp[i-1]
  elif i-2 not in a and i-1 in a:
    dp[i]=dp[i-2]
  elif i-2 in a and i-1 not in a:
    dp[i]=dp[i-1]
  else:
    dp[i]=0
print(dp[n]%(10**9+7))    