#include <algorithm>
#include <cmath>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <iostream>
#include <string>
#include <vector>
#define SZ(x) ((int)(x).size())
#define FOR(it, c) for(__typeof((c).begin()) it = (c).begin(); it != (c).end(); ++it)
using namespace std;
typedef long long LL;

const int N = 1e5+5;
vector<int> a[N];
int mark[N], mark2[N];

int getparent(int x, int y) {
  if (SZ(a[x]) == 1) {
    return y == -1? a[x][0] : 0;
  }
  if (SZ(a[x]) == 2) {
    return y == -1? 0 : a[x][0] + a[x][1] - y;
  }
  return 0;
}

int main(void) {
  int n;
  scanf("%d", &n);
  for(int i=1;i<n;i++) {
    int x, y;
    scanf("%d%d", &x, &y);
    a[x].push_back(y);
    a[y].push_back(x);
  }
  for(int i=1;i<=n;i++) {
    if(SZ(a[i])==1 && mark[i]==0) {
      int x = i, y = -1, z;
      mark[x] = 1;
      while ((z = getparent(x, y)) > 0) {
        if(SZ(a[z]) > 2) break;
        mark[z] = 1;
        y = x;
        x = z;
      }
    }
  }
  int d[3]={}, ok = 1;
  for(int i=1;i<=n;i++) {
    if (mark[i]==0) {
      int deg=0;
      FOR(it, a[i]) if(mark[*it]==0) ++deg;
      if (deg==1 && SZ(a[i])<=3) mark2[i] = 1;
    }
  }
  for(int i=1;i<=n;i++) mark[i] |= mark2[i];
  for(int i=1;i<=n;i++) {
    if (mark[i]==0) {
      int deg=0;
      FOR(it, a[i]) if(mark[*it]==0) ++deg;
      if (deg<=2) ++d[deg];
      else ok=0;
    }
  }
  if(d[1]>2) ok = 0;
  puts(ok? "Yes":"No");
  return 0;
}