using System;
using System.Collections;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Numerics;
namespace Tasks
{
public class E
{
public static void Main(string[] args)
{
var sw = new StreamWriter(Console.OpenStandardOutput()) { AutoFlush = false };
Console.SetOut(sw);
Solve();
Console.Out.Flush();
}
public static void Solve()
{
var (N, Q) = Scanner.Scan<int, int>();
var dsu = new DisjointSetUnion(N + 1);
for (var i = 0; i < Q; i++)
{
var (l, r) = Scanner.Scan<int, int>();
l--;
dsu.Merge(l, r);
}
var answer = dsu.IsSame(0, N);
Console.WriteLine(answer ? "Yes" : "No");
}
public class DisjointSetUnion
{
private readonly int _length;
private readonly int[] _parentOrSize;
public DisjointSetUnion(int length)
{
if (length < 0) throw new ArgumentOutOfRangeException(nameof(length));
_length = length;
_parentOrSize = new int[_length];
Array.Fill(_parentOrSize, -1);
}
public int Merge(int u, int v)
{
if (u < 0 || _length <= u) throw new ArgumentOutOfRangeException(nameof(u));
if (v < 0 || _length <= v) throw new ArgumentOutOfRangeException(nameof(v));
var (x, y) = (LeaderOf(u), LeaderOf(v));
if (x == y) return x;
if (-_parentOrSize[x] < -_parentOrSize[y]) (x, y) = (y, x);
_parentOrSize[x] += _parentOrSize[y];
_parentOrSize[y] = x;
return x;
}
public bool IsSame(int u, int v)
{
if (u < 0 || _length <= u) throw new ArgumentOutOfRangeException(nameof(u));
if (v < 0 || _length <= v) throw new ArgumentOutOfRangeException(nameof(v));
return LeaderOf(u) == LeaderOf(v);
}
public int LeaderOf(int v)
{
if (v < 0 || _length <= v) throw new ArgumentOutOfRangeException(nameof(v));
if (_parentOrSize[v] < 0) return v;
return _parentOrSize[v] = LeaderOf(_parentOrSize[v]);
}
public int SizeOf(int v)
{
if (v < 0 || _length <= v) throw new ArgumentOutOfRangeException(nameof(v));
return -_parentOrSize[LeaderOf(v)];
}
public IEnumerable<IReadOnlyCollection<int>> GetGroups()
{
var result = new List<int>[_length].Select(x => new List<int>()).ToArray();
for (var i = 0; i < _length; i++) result[LeaderOf(i)].Add(i);
return result.Where(x => x.Count > 0);
}
}
public static class Scanner
{
public static string ScanLine() => Console.ReadLine()?.Trim() ?? string.Empty;
public static string[] Scan() => ScanLine().Split(' ');
public static T Scan<T>() where T : IConvertible => Convert<T>(Scan()[0]);
public static (T1, T2) Scan<T1, T2>() where T1 : IConvertible where T2 : IConvertible
{
var line = Scan();
return (Convert<T1>(line[0]), Convert<T2>(line[1]));
}
public static (T1, T2, T3) Scan<T1, T2, T3>() where T1 : IConvertible where T2 : IConvertible where T3 : IConvertible
{
var line = Scan();
return (Convert<T1>(line[0]), Convert<T2>(line[1]), Convert<T3>(line[2]));
}
public static (T1, T2, T3, T4) Scan<T1, T2, T3, T4>() where T1 : IConvertible where T2 : IConvertible where T3 : IConvertible where T4 : IConvertible
{
var line = Scan();
return (Convert<T1>(line[0]), Convert<T2>(line[1]), Convert<T3>(line[2]), Convert<T4>(line[3]));
}
public static (T1, T2, T3, T4, T5) Scan<T1, T2, T3, T4, T5>() where T1 : IConvertible where T2 : IConvertible where T3 : IConvertible where T4 : IConvertible where T5 : IConvertible
{
var line = Scan();
return (Convert<T1>(line[0]), Convert<T2>(line[1]), Convert<T3>(line[2]), Convert<T4>(line[3]), Convert<T5>(line[4]));
}
public static (T1, T2, T3, T4, T5, T6) Scan<T1, T2, T3, T4, T5, T6>() where T1 : IConvertible where T2 : IConvertible where T3 : IConvertible where T4 : IConvertible where T5 : IConvertible where T6 : IConvertible
{
var line = Scan();
return (Convert<T1>(line[0]), Convert<T2>(line[1]), Convert<T3>(line[2]), Convert<T4>(line[3]), Convert<T5>(line[4]), Convert<T6>(line[5]));
}
public static IEnumerable<T> ScanEnumerable<T>() where T : IConvertible => Scan().Select(Convert<T>);
private static T Convert<T>(string value) where T : IConvertible => (T)System.Convert.ChangeType(value, typeof(T));
}
}
}