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

dp=[0]*(n+1)
#dp=[-1]*(n+1)
dp[0]=1
if 1 not in mList:
  dp[1]=1

for i in range(2,n+1):
  if i in mList: continue
  dp[i]+=dp[i-1]
  dp[i]+=dp[i-2]
  dp[i]%=1000000007

#def calc(i):
#  if dp[i]!=-1: return dp[i]
#  if i in mList:
#    dp[i]=0
#    return dp[i]
#  dp[i]=calc(i-1)+calc(i-2)
#  dp[i]%=1000000007
#  return dp[i]

#print(calc(n))
print(dp[n])
