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#include <iostream>
#include <algorithm>
#include <vector>
#include <bitset>
#include <cstdio>
#include <cstdlib>
#define DN 200005
#define LL long long
#define x first
#define y second
using namespace std;

typedef pair<int,int> per;
typedef vector<int>::iterator it;

int n,d[DN],pre[DN],inc[DN];
vector<int> gr[DN];
bitset<DN> viz;

void dfs(int s) {//Search for the longest chain in a tree
    //cout<<s<<": ";
    for(it i=gr[s].begin(); i!=gr[s].end(); ++i) {
        //cout<<*i<<' '<<d[*i]<<' ';
        if(!d[*i]) {
            d[*i]=1+d[s];
            pre[*i]=s;
            dfs(*i);
        }
    }
    //cout<<'\n';
}

int ich(int s) {//returns 1 if there's a chain starting in node s
    viz[s]=1;
    if(gr[s].size()>2) return 0;
    for(it i=gr[s].begin(); i!=gr[s].end(); ++i) if(!viz[*i]) return ich(*i);
    return 1;
}

int one_row(int s) {//returns 1 if starting from node s all sons can be put on one line
    if(gr[s].size()>3) return 0;
    viz[s]=1;
    int ok=1;
    for(it i=gr[s].begin(); i!=gr[s].end(); ++i) if(!inc[*i]) ok&=ich(*i);
    return ok;
}

int main() {
  //freopen("input.txt","r",stdin);
  cin.sync_with_stdio(false);
  cin>>n;
  if(n==1) {
    cout<<"Yes";
    return 0;
  }
  for(int i=1; i<n; ++i) {
    int a,b; cin>>a>>b;
    gr[a].push_back(b);
    gr[b].push_back(a);
  }
  d[1]=1;
  dfs(1);
  int n1,dm=0;
  for(int i=1; i<=n; ++i) if(d[i]>dm) {
    dm=d[i];
    n1=i;
  }
  for(int i=1; i<=n; ++i) d[i]=0;
  d[n1]=1;
  dfs(n1);
  int n2;dm=0;
  for(int i=1; i<=n; ++i) if(i!=n1 && d[i]>dm) {
    dm=d[i];
    n2=i;
  }
  //n1 n2 ends of the longest chain
  inc[n1]=viz[n1]=1;
  for(;n2!=n1; n2=pre[n2]) inc[n2]=viz[n2]=1;
  string r="Yes";
  for(int i=1; i<=n; ++i) if(inc[i]) {
    int ok=1;
    for(it j=gr[i].begin(); j!=gr[i].end(); ++j) if(!inc[*j] && !one_row(*j)) {
        ok=0;
        //cout<<i<<' '<<*j<<'\n';
        break;
    }
    if(!ok) {
        r="No\n";
        break;
    }
  }
  cout<<r;
}