import std.stdio, std.conv, std.string, std.array, std.range, std.algorithm, std.container;
import std.math, std.random, std.bigint, std.datetime, std.format;
void main(string[] args){ if(args.length > 1) if(args[1] == "-debug") DEBUG = 1; solve(); }
void log()(){ writeln(""); } void log(T, A ...)(T t, lazy A a){ if(DEBUG) write(t, " "), log(a); } bool DEBUG = 0; 
string read(){ static string[] ss; while(!ss.length) ss = readln.chomp.split; string res = ss[0]; ss.popFront; return res; }
// ----- ----- ----- ----- ----- ----- ----- ----- ----- ----- ----- ----- //
void solve(){
	int n = read.to!int;
	
	Node[] nodes;
	foreach(i; 0 .. n) nodes ~= new Node(i);
	
	foreach(i; 0 .. n - 1){
		int u = read.to!int - 1;
		int v = read.to!int - 1;
		nodes[u].nodes ~= nodes[v];
		nodes[v].nodes ~= nodes[u];
	}
	
	int f = 0;
	foreach(nd; nodes){
		if(nd.nodes.length == 2) f = 1;
	}
	
	if(f == 1) "NO".writeln;
	else "YES".writeln;
	
}
/*
A1: YES if and only if there are no vertex with degree 2.



*/

class Node{
	int id;
	Node[] nodes;
	this(int id){
		this.id = id;
	}
}
