#include <atcoder/all>
#include <bits/stdc++.h>
using namespace std;
using ll=long long;
using ull=unsigned long long;
#define rep(i,n) for(int i=0; i<(n); i++)
using mll=atcoder::static_modint<1000000007>;

int N;
vector<vector<int>> E;
vector<int> I,P;
int diam, diamcent, diamcent2;
vector<int> D, pD;

int main(){
  scanf("%d",&N);
  E.resize(N);
  rep(i,N-1){
    int u,v; scanf("%d%d",&u,&v); u--; v--;
    E[u].push_back(v);
    E[v].push_back(u);
  }
  P.assign(N,-1);
  queue<int> Q; Q.push(0);
  while(Q.size()){
    int p=Q.front(); Q.pop();
    I.push_back(p);
    for(int e:E[p]) if(P[p]!=e){ P[e]=p; Q.push(e); }
  }
  reverse(I.begin(),I.end());

  D.assign(N,0);
  diam=0; diamcent=-1;
  pD.assign(N,-1);

  for(int i:I) if(i!=0){
    if(diam<D[i]+D[P[i]]){ diam=D[i]+D[P[i]]; diamcent=i; }
    if(D[P[i]]<D[i]+1){ D[P[i]]=D[i]+1; pD[P[i]]=i; }
  }
  if(diam<D[0]){ diam=D[0]; diamcent=0; }
  while(diam>D[diamcent]*2) diamcent=P[diamcent];
  while(diam<D[diamcent]*2) diamcent=pD[diamcent];
  if(diam>D[diamcent]*2) diamcent2=P[diamcent]; else diamcent2=diamcent;

  P.assign(N,-1);
  D.assign(N,-1);
  Q.push(diamcent); if(diamcent!=diamcent2) Q.push(diamcent2);
  P[diamcent]=diamcent2; P[diamcent2]=diamcent;
  D[diamcent]=D[diamcent2]=diam/2;
  while(Q.size()){
    int p=Q.front(); Q.pop();
    for(int e:E[p]) if(P[p]!=e){ P[e]=p; D[e]=D[p]-1; Q.push(e); }
    if(E[p].size()==1) if(D[p]!=0){ printf("No\n"); return 0; }
  }
  
  printf("Yes\n");
  return 0;
}