from sys import stdin
nii=lambda:map(int,stdin.readline().split())
lnii=lambda:list(map(int,stdin.readline().split()))

n,m=nii()

mod=10**9+7

dp=[-1 for i in range(n+1)]
dp[0]=1
dp[1]=1
for i in range(m):
  a=int(input())
  dp[a]=0

for i in range(2,n+1):
  if dp[i]==0:
    continue
  num=dp[i-2]+dp[i-1]
  num%=mod
  dp[i]=num

print(dp[-1]) from sys import stdin nii=lambda:map(int,stdin.readline().split()) nii lambda:map(int,stdin.readline().split()) map(int,stdin.readline().split()) map int stdin.readline().split() stdin.readline().split stdin.readline() stdin.readline stdin readline split lnii=lambda:list(map(int,stdin.readline().split())) lnii lambda:list(map(int,stdin.readline().split())) list(map(int,stdin.readline().split())) list map(int,stdin.readline().split()) map int stdin.readline().split() stdin.readline().split stdin.readline() stdin.readline stdin readline split n,m=nii() n nii() nii m mod=10**9+7 mod 10**9+7 10**9 10 9 7 -1 for i in range(n+1) for i in range(n+1) i range(n+1) range n+1 n 1 for i in range(n+1) -1 dp=[-1 for i in range(n+1)] dp [-1 for i in range(n+1)] dp[0]=1 dp[0] dp 0 1 dp[1]=1 dp[1] dp 1 1 for i in range(m):
  a=int(input())
  dp[a]=0 i range(m) range m a=int(input()) a int(input()) int input() input dp[a]=0 dp[a] dp a 0 for i in range(2,n+1):
  if dp[i]==0:
    continue
  num=dp[i-2]+dp[i-1]
  num%=mod
  dp[i]=num i range(2,n+1) range 2 n+1 n 1 if dp[i]==0:
    continue
   dp[i]==0 dp[i] dp i 0 continue num=dp[i-2]+dp[i-1] num dp[i-2]+dp[i-1] dp[i-2] dp i-2 i 2 dp[i-1] dp i-1 i 1 num%=mod num mod dp[i]=num dp[i] dp i num print(dp[-1]) print dp[-1] dp -1 nii=lambda:map(int,stdin.readline().split()) lambda:map(int,stdin.readline().split()) nii num=dp[i-2]+dp[i-1] dp[i-2]+dp[i-1] num dp=[-1 for i in range(n+1)] [-1 for i in range(n+1)] dp m=nii() nii() m mod=10**9+7 10**9+7 mod n,m=nii() nii() n num%=mod mod num a=int(input()) int(input()) a lnii=lambda:list(map(int,stdin.readline().split())) lambda:list(map(int,stdin.readline().split())) lnii
from sys import stdin
nii=lambda:map(int,stdin.readline().split())
lnii=lambda:list(map(int,stdin.readline().split()))

n,m=nii()

mod=10**9+7

dp=[-1 for i in range(n+1)]
dp[0]=1
dp[1]=1
for i in range(m):
  a=int(input())
  dp[a]=0

for i in range(2,n+1):
  if dp[i]==0:
    continue
  num=dp[i-2]+dp[i-1]
  num%=mod
  dp[i]=num

print(dp[-1])