#include <bits/stdc++.h>
using namespace std;
struct Edge {
  int y, t;
} e[200002];
bool vis[100002];
char ch;
int n, x, y, h[100002], ep, sz[100002], d[100002], w;
inline void read(int &x) {
  x = 0;
  do {
    ch = getchar();
  } while (ch < '0' || '9' < ch);
  do {
    x = x * 10 + ch - '0';
    ch = getchar();
  } while ('0' <= ch && ch <= '9');
}
inline void AddEdge(const int &x, const int &y) {
  e[++ep].y = y;
  e[ep].t = h[x];
  h[x] = ep;
}
void dfs(const int &x) {
  vis[x] = true;
  for (int i = h[x]; i; i = e[i].t)
    if (!vis[e[i].y] && sz[e[i].y] <= 2) dfs(e[i].y);
}
int main(void) {
  read(n);
  for (int i = 1; i < n; i++)
    read(x), read(y), AddEdge(x, y), AddEdge(y, x), sz[x]++, sz[y]++;
  for (int i = 1; i <= n; i++)
    if (sz[i] == 1) dfs(i);
  for (int i = 1; i <= n; i++)
    if (!vis[i]) {
      for (int j = h[i]; j; j = e[j].t)
        if (vis[e[j].y]) {
          d[i] = min(d[i] + 1, 2);
        }
    }
  for (int i = 1; i <= n; i++)
    if (!vis[i]) {
      w = 0;
      for (int j = h[i]; j; j = e[j].t)
        if (!vis[e[j].y] && sz[e[j].y] - d[e[j].y] > 1) w++;
      if (w > 2) {
        puts("No");
        return 0;
      }
    }
  puts("Yes");
  return 0;
}
