import core.bitop;
import std.algorithm;
import std.array;
import std.ascii;
import std.container;
import std.conv;
import std.format;
import std.math;
import std.range;
import std.stdio;
import std.string;
import std.typecons;

alias A = Tuple!(int, "to", int, "idx");

bool[] done;
int n, m;
A[][] adj;
void dfs(int now)
{
  foreach (next; adj[now]) {
    if (done[next.idx]) {
      continue;
    }
    done[next.idx] = true;
    dfs(next.to);
    break;
  }
}

void main()
{
  auto v = readln.chomp.split.map!(to!int);
  n = v.front;
  m = v.back;
  adj = new A[][](n);
  foreach (i; 0..m) {
    auto s = readln.chomp.split.map!(to!int);
    int a = s.front;
    int b = s.back;
    adj[a] ~= A(b, i);
    adj[b] ~= A(a, i);
  }
  int cnt = 0;
  foreach (t; adj) {
    cnt += t.length % 2 == 1;
  }
  bool ans = cnt == 0 || cnt == 2;
  enum R = ["NO", "YES"];
  R[ans].writeln;
}