#include <iostream>
#include <iomanip>
#include <stdio.h>
#include <vector>
#include <string.h>
#include <set>
using namespace std;

#define pb push_back
#define mp make_pair

int par[1005];
vector<int> g[1005];
bool child[1005];

void dfs(int st, int parent = -1) {
    par[st] = parent;
    for (int i=0; i<g[st].size(); i++) {
        int nxt = g[st][i];
        if (nxt != parent) { dfs(nxt, st); }
    }
}

int main() {

    int q1, q2;
    int m, n;
    vector<int> c;
    set<int> asdf;
    while (scanf("%d", &n) != EOF) {
        memset(par, 0, sizeof par);
        memset(child, false, sizeof child);
        if ( n == 1) { cout << "YES" << endl; continue; }
        c.clear();
        asdf.clear();
        for (int i=0; i<1005; i++) {
            g[i].clear();
        }
        for(int i=0; i < n-1; i++) {
            scanf("%d %d", &q1, &q2);
            g[q1].pb(q2);
            g[q2].pb(q1);
        }
        dfs(1);
        for (int i=2; i <= n; i++) {
            if (g[i].size() == 1) { asdf.insert(par[i]); }
        }

        if (asdf.size() >= 2) { cout << "NO" << endl;}
        else { cout << "YES" << endl;}
    }
}