import std.stdio;
import std.conv, std.array, std.algorithm, std.string;
import std.math, std.random, std.range, std.datetime;
import std.bigint;
string read(){ static string[] ss; while(!ss.length) ss = readln.chomp.split; string res = ss[0]; ss.popFront; return res; }

void main(){
	int n = read.to!int;
	int m = read.to!int;
	
	bool[] xs;
	xs.length = n + 1;
	foreach(i; 1 .. n + 1) xs[i] = 0;
	foreach(i; 0 .. m){
		int a = read.to!int;
		int b = read.to!int;
		xs[a] = !xs[a];
		xs[b] = !xs[b];
		}
	
	string ans = "YES";
	foreach(x; xs) if(x) ans = "NO";
	
	ans.writeln;
	
	}