#include <iostream>
#include<vector>
#include<algorithm>
#include<string>
#include<map>
#include<set>
#include<stack>
#include<queue>
#include<math.h>
using namespace std;
typedef long long ll;
#define int long long
#define double long double
typedef vector<int> VI;
typedef pair<int, int> pii;
typedef vector<pii> VP;
typedef vector<string> VS;
typedef priority_queue<int> PQ;
template<class T>bool chmax(T &a, const T &b) { if (a < b) { a = b; return 1; } return 0; }
template<class T>bool chmin(T &a, const T &b) { if (b < a) { a = b; return 1; } return 0; }
#define fore(i,a) for(auto &i:a)
#define REP(i,n) for(int i=0;i<n;i++)
#define eREP(i,n) for(int i=0;i<=n;i++)
#define FOR(i,a,b) for(int i=(a);i<(b);++i)
#define eFOR(i,a,b) for(int i=(a);i<=(b);++i)
#define SORT(c) sort((c).begin(),(c).end())
#define rSORT(c) sort((c).rbegin(),(c).rend())
#define LB(x,a) lower_bound((x).begin(),(x).end(),(a))
#define UB(x,a) upper_bound((x).begin(),(x).end(),(a))
#define INF 1000000000
#define LLINF 9223372036854775807
#define mod 1000000007
#define eps 1e-12 
//priority_queue<int,vector<int>, greater<int> > q2;



signed main() {
	cin.tie(0);
	ios::sync_with_stdio(false);

	int N, K; cin >> N >> K;
	VI A(K);
	REP(i, K)cin >> A[i];
	bool F = true;
	int X = -1;
	REP(i, K) {
		FOR(j, i + 1, K) {
			int tmp = A[j] - A[i];
			if (tmp == 5) {
				if (A[i] - 1 == 1)F = false;
				X = A[i] - 1;
			}
			if (tmp == 3) {
				if (A[i] - 2 == 1)F = false;
				X = A[i] - 2;
			}
			if (tmp == 1) {
				if (A[i] - 3 == 1)F = false;
				X = A[i] - 3;
			}
		}
	}
	
	X -= 8;
	if (X >= 1)F = false;
	cout << (F ? "Yes" : "No") << endl;

	return 0;
}