Limak is a little bear who learns to draw. People usually start with houses, fences and flowers but why would bears do it? Limak lives in the forest and he decides to draw a tree.

Recall that tree is a connected graph consisting of n vertices and n - 1 edges.

Limak chose a tree with n vertices. He has infinite strip of paper with two parallel rows of dots. Little bear wants to assign vertices of a tree to some n distinct dots on a paper so that edges would intersect only at their endpoints — drawn tree must be planar. Below you can see one of correct drawings for the first sample test.

<image>

Is it possible for Limak to draw chosen tree?

Input

The first line contains single integer n (1 ≤ n ≤ 105).

Next n - 1 lines contain description of a tree. i-th of them contains two space-separated integers ai and bi (1 ≤ ai, bi ≤ n, ai ≠ bi) denoting an edge between vertices ai and bi. It's guaranteed that given description forms a tree.

Output

Print "Yes" (without the quotes) if Limak can draw chosen tree. Otherwise, print "No" (without the quotes).

Examples

Input

8
1 2
1 3
1 6
6 4
6 7
6 5
7 8


Output

Yes


Input

13
1 2
1 3
1 4
2 5
2 6
2 7
3 8
3 9
3 10
4 11
4 12
4 13


Output

No
import javafx.util.Pair;

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.text.DecimalFormat;
import java.text.NumberFormat;
import java.util.*;

public class Main {
    public static void main(String[] args) {
        ConsoleIO io = new ConsoleIO();
        new Main(io).solve();
        io.flush();
    }

    ConsoleIO io;

    Main(ConsoleIO io) {
        this.io = io;
    }

    public void solve() {
        int n = io.readInt();
        int[] deg = new int[n], deg2 = new int[n];
        int[] par = new int[n];
        for (int i = 0; i < n-1; i++) {
            int[] l = io.readIntArray();
            int q = l[0] - 1;
            int w = l[1] - 1;
            deg2[q] = ++deg[q];
            deg2[w] = ++deg[w];
            par[q]+=w;
            par[w]+=q;
        }
        for(int i = 0;i<n;i++) {
            int cur = i;
            while (deg[cur] == 1 && deg2[cur] < 3) {
                deg[cur] = 0;
                par[par[cur]] -= cur;
                deg[par[cur]]--;
                cur = par[cur];
            }
        }
        for (int i = 0; i < n; i++)
            if (deg[i] == 1 && deg2[i]<4) {
                deg[par[i]]--;
                deg2[par[i]] = 4;
            }
        int ok = 1;
        for (int i = 0; i < n; i++)
            if (deg[i] > 2) ok = 0;
        io.writeLine(ok == 1 ? "Yes" : "No");
    }
}

class ConsoleIO {
    BufferedReader br;
    PrintWriter out;
    public ConsoleIO(){br = new BufferedReader(new InputStreamReader(System.in));out = new PrintWriter(System.out);}
    public void flush(){
        this.out.close();
    }
    public void writeLine(String s) {
        this.out.println(s);
    }
    public void writeInt(int a) {this.out.print(a);this.out.print(' ');}
    public void writeWord(String s){
        this.out.print(s);
    }
    public String readLine() {try {return br.readLine();}catch (Exception ex){ return "";}}
    public long readLong() {
        return Long.parseLong(this.readLine());
    }
    public int readInt() {
        return Integer.parseInt(this.readLine().trim());
    }
    public long[] readLongArray() {
        String[]n=this.readLine().trim().split(" ");long[]r=new long[n.length];
        for(int i=0;i<n.length;i++)r[i]=Long.parseLong(n[i]);
        return r;
    }
    public int[] readIntArray() {
        String[]n=this.readLine().trim().split("\\s+");int[]r=new int[n.length];
        for(int i=0;i<n.length;i++)r[i]=Integer.parseInt(n[i]);
        return r;
    }
}

