#include <bits/stdc++.h>
#define rep(i,n) for(int i=0;i<(n);++i)
using namespace std;
typedef long long ll;

int main()
{
    int n,m;
    cin>>n>>m;
    vector<int>broken(n+1);
    rep(i,m){
        int a;
        cin>>a;
        broken[a]=1;
    }
    vector<int> dp(n+2);
    const int mod=10000000007
    dp[n]=1;
    for(int i=n-1;i>=0;i++){
        if (broken[i]){
            dp[i]=0;
            continue;
        }
        dp[i]=(dp[i+1]+dp[i+2])%mod;
    }
    cout<<dp[0]<<endl;
}
