import sys
N,M=map(int,input().split())
dp=[1]*N
listA=[]
for i in range(M):
  a=int(input())
  listA+=[a]
  dp[a-1]=0
for i in range(1,M):
  if listA[i]==listA[i-1]:
    print(0)
    sys.exit()
setA=set(listA)    
if (1 not in setA) and (2 not in setA):
  dp[1]=2
for i in range(2,N):
  if i+1 not in setA:
    dp[i]=dp[i-1]+dp[i-2]
ans=dp[-1]%(10**9+7)
print(ans)