#include<iostream>
#include<vector>
#include <algorithm>

using namespace std;

using ll = long long;
using ull = unsigned long long;

int main(){
 ull n;
 int k;
 cin >> n >> k;
 vector<ull> a(k + 1 , 0);

 for(int i = 1; i <= k; i++){
  cin >> a[i];
  a[i] += 10;
 }
 ull mx =*max_element(a.begin() , a.end());
 vector<int> check(mx + 50 , 0);

 for(int i = 1; i <= k; i++){
  check[a[i]] = 1;
 }
 
 for(ull i = mx; i >= 10; i--){
   if(check[a[i] + 5] == 1)check[a[i] - 1] = 1;
   if(check[a[i] + 3] == 1)check[a[i] + 4] = 1;
   if(check[a[i] + 1] == 1)check[a[i] - 3] = 1;
 }

 if(check[11] == 1)cout << "No" << endl;
 else cout << "Yes" << endl;

return 0;

}