#include <bits/stdc++.h>
using namespace std;
const int N = 1e5 + 5;
vector<int> a[N];
int mark[N], mark2[N];
int getparent(int x, int y) {
  if (((int)(a[x]).size()) == 1) {
    return y == -1 ? a[x][0] : 0;
  }
  if (((int)(a[x]).size()) == 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 (((int)(a[i]).size()) == 1 && mark[i] == 0) {
      int x = i, y = -1, z;
      mark[x] = 1;
      while ((z = getparent(x, y)) > 0) {
        if (((int)(a[z]).size()) > 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 (__typeof((a[i]).begin()) it = (a[i]).begin(); it != (a[i]).end();
           ++it)
        if (mark[*it] == 0) ++deg;
      if (deg == 1 && ((int)(a[i]).size()) <= 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 (__typeof((a[i]).begin()) it = (a[i]).begin(); it != (a[i]).end();
           ++it)
        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;
}
