#define _USE_MATH_DEFINES
#include <bits/stdc++.h>
using namespace std;
#define FOR(i,m,n) for(int i=(m);i<(n);++i)
#define REP(i,n) FOR(i,0,n)
#define ALL(v) (v).begin(),(v).end()
using ll = long long;
constexpr int INF = 0x3f3f3f3f;
constexpr ll LINF = 0x3f3f3f3f3f3f3f3fLL;
constexpr double EPS = 1e-8;
constexpr int MOD = 1000000007;
// constexpr int MOD = 998244353;
constexpr int dy[] = {1, 0, -1, 0}, dx[] = {0, -1, 0, 1};
constexpr int dy8[] = {1, 1, 0, -1, -1, -1, 0, 1}, dx8[] = {0, -1, -1, -1, 0, 1, 1, 1};
template <typename T, typename U> inline bool chmax(T &a, U b) { return a < b ? (a = b, true) : false; }
template <typename T, typename U> inline bool chmin(T &a, U b) { return a > b ? (a = b, true) : false; }
struct IOSetup {
  IOSetup() {
    cin.tie(nullptr);
    ios_base::sync_with_stdio(false);
    cout << fixed << setprecision(20);
  }
} iosetup;

int main() {
  ll n; int k; cin >> n >> k;
  vector<ll> a(k); REP(i, k) cin >> a[i];
  REP(i, k - 1) {
    if (a[i] >= 10000 && a[i + 1] - a[i] <= 5) {
      assert(false);
      cout << "No\n";
      return 0;
    }
  }
  int x = min(n, 20000LL);
  vector<bool> ng(x + 1, false);
  REP(i, k) {
    if (a[i] <= x) ng[a[i]] = true;
  }
  for (int i = x - 1; i >= 1; --i) {
    if (i + 6 <= x && ng[i + 1] && ng[i + 6]) ng[i] = true;
    if (i + 5 <= x && ng[i + 2] && ng[i + 5]) ng[i] = true;
    if (i + 4 <= x && ng[i + 3] && ng[i + 4]) ng[i] = true;
  }
  cout << (ng[1] ? "No\n" : "Yes\n");
  return 0;
}