#define _USE_MATH_DEFINES
#include <bits/stdc++.h>
using namespace std;
signed main() {
  int n, k;
  cin >> n >> k;
  vector<long long> a(k);
  for (auto& x : a) cin >> x;
  int m = min(n, 1000);
  vector<int> dp(m + 1, 1);
  for (int i = m; i >= 1; i--) {
    for (auto x : a) if (x == i) dp[i] = 0;
    if (dp[i]) {
      if (i + 1 <= m && i + 6 <= m) {
        if (!dp[i + 1] && !dp[i + 6]) dp[i] = 0;
      }
      if (i + 2 <= m && i + 5 <= m) {
        if (!dp[i + 2] && !dp[i + 5]) dp[i] = 0;
      }
      if (i + 3 <= m && i + 4 <= m) {
        if (!dp[i + 3] && !dp[i + 4]) dp[i] = 0;
      }
    }
  }
  if (!dp[1]) {
    cout << "No" << endl;
    return 0;
  }
  for (auto x : a) for (auto y : a) {
    long long dif = abs(x - y);
    if (dif == 1 || dif == 3 || dif == 5) {
      long long mi = min(x, y);
      if (mi - 8 >= 1) {
        cout << "No" << endl;
        return 0;
      }
    }
  }
  cout << "Yes" << endl;
  return 0;
}