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;

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