#include<bits/stdc++.h>
using namespace std;
#define rep(i,n) for(ll i=0;i<n;i++)
#define repl(i,l,r) for(ll i=(l);i<(r);i++)
#define per(i,n) for(ll i=n-1;i>=0;i--)
#define perl(i,r,l) for(ll i=r-1;i>=l;i--)
#define fi first
#define se second
#define pb push_back
#define ins insert
#define pqueue(x) priority_queue<x,vector<x>,greater<x>>
#define all(x) (x).begin(),(x).end()
#define CST(x) cout<<fixed<<setprecision(x)
#define vtpl(x,y,z) vector<tuple<x,y,z>>
#define rev(x) reverse(x);
using ll=long long;
using vl=vector<ll>;
using vvl=vector<vector<ll>>;
using pl=pair<ll,ll>;
using vpl=vector<pl>;
using vvpl=vector<vpl>;
const ll MOD=1000000007;
const ll MOD9=998244353;
const int inf=1e9+10;
const ll INF=4e18;
const ll dy[9]={0,0,1,-1,1,1,-1,-1,0};
const ll dx[9]={1,-1,0,0,1,-1,1,-1,0};
template<class T> inline bool chmin(T& a, T b) {
    if (a > b) {
        a = b;
        return true;
    }
    return false;
}
template<class T> inline bool chmax(T& a, T b) {
    if (a < b) {
        a = b;
        return true;
    }
    return false;
}


int main(){
    ll n,k;cin >> n >>k;
    vl a(k);rep(i,k)cin >> a[i];rev(all(a));
    for(int i=0;i<=a.size();i++){

    }

    set<ll> st;
    rep(i,k)st.insert(a[i]);
    for(auto itr=st.rbegin();itr!=st.rend();itr++){
        ll p=*itr;
        if(st.count(p+1))if(p-3>0)st.insert(p-3);
        if(st.count(p+3))if(p-2>0)st.insert(p-2);
        if(st.count(p+5))if(p-1>0)st.insert(p-1);
    }
    if(st.count(1))cout << "No" <<endl;
    else cout << "No" <<endl;
    //for(auto p:st)cout << p <<endl;
}