#include<bits/stdc++.h>
using namespace std;
#define ll long long
const ll MOD=1000000007;
ll n,m;
ll dp[100009];
int main(){
scanf("%lld %lld",&n,&m);
for(int i=1;i<=m;++i){ll a;scanf("%lld",&a);dp[a]=-1;}
dp[0]=1;
if(dp[1]!=-1)dp[1]=1;
for(int i=2;i<=n;++i){
if(dp[i]-1)continue;
if(dp[i-1]!=-1 && dp[i-2]-1){
dp[i]=dp[i-1]%MOD;
}
if(dp[i-1]-1 && dp[i-2]!=-1){
dp[i]=dp[i-2]%MOD;
}
if(dp[i-1]!=-1 && dp[i-2]!=-1){
dp[i]=(dp[i-1]+dp[i-2])%MOD;
}
if(dp[i-1]-1 && dp[i-2]==-1){
dp[i]=0;
}
}
printf("%lld\n",dp[n]%MOD);
}