n,m=map(int,input().split())
lst=[int(input()) for i in range(m)]
DP=[0]*(n+1)
temp=0
DP[0]=1
for i in range(1, n+1):
  if i==1 and i not in lst:
    DP[i]=1
  elif i==1 and i in lst:
    DP[i]=0
  elif i in lst:
    DP[i]=0
  else:
    DP[i]=DP[i-1]+DP[i-2]
print(DP[n]%1000000007)