#include <iostream>
#include <vector>
#include <algorithm>
#include <cmath>
#include <queue>
#include <string>
#include <map>
#include <set>
#include <stack>
#include <tuple>
#include <deque>
#include <array>
#include <numeric>
#include <bitset>
#include <iomanip>
#include <cassert>
#include <chrono>
#include <random>
#include <limits>
#include <iterator>
#include <functional>
#include <sstream>
#include <fstream>
#include <complex>
#include <cstring>
#include <unordered_map>
using namespace std;

using ll = long long;
using P = pair<int, int>;
constexpr int INF = 1001001001;
constexpr int mod = 1000000007;
// constexpr int mod = 998244353;

template<class T>
inline bool chmax(T& x, T y){
    if(x < y){
        x = y;
        return true;
    }
    return false;
}
template<class T>
inline bool chmin(T& x, T y){
    if(x > y){
        x = y;
        return true;
    }
    return false;
}

int main(){
    ios::sync_with_stdio(false);
    cin.tie(nullptr);

    ll N;
    int K;
    cin >> N >> K;
    vector<ll> A(K);
    for(int i = 0; i < K; ++i)  cin >> A[i];
    
    if(K == 1){
        cout << "Yes\n";
        return 0;
    }

    if(A.back() > 1000){
        for(int i = K - 2; i >= 0; --i){
            if(A[i + 1] <= 1000){
                K = i + 2;
                break;
            }
            int gap = A[i + 1] - A[i];
            if(gap == 1 || gap == 3 || gap == 5){
                cout << "No\n";
                return 0;
            }
        }
    }

    vector<bool> ban(1010);
    for(int i = 0; i < K; ++i)  ban[A[i]] = true;
    for(int i = 1000; i >= 2; --i){
        if(!ban[i]) continue;
        if(ban[i + 1] && i - 3 > 0){
            ban[i - 3] = true;
        }
        if(ban[i + 3] && i - 2 > 0){
            ban[i - 2] = true;
        }
        if(ban[i + 5] && i - 1 > 0){
            ban[i - 1] = true;
        }
    }
    if(ban[1])  cout << "No\n";
    else    cout << "Yes\n";

    return 0;
}