/*
validation
*/

#include <bits/stdc++.h>

#include "testlib.h"

#include <atcoder/dsu>

using ll = long long;

const ll n_min = 1, n_max = 300'000;

int main() {
    registerValidation();
    const ll n = inf.readLong(n_min, n_max);
    inf.readEoln();
    atcoder::dsu uf(n);
    for(int i = 0; i < n-1; i++) {
        const ll u = inf.readLong(1, n) - 1;
        inf.readSpace();
        const ll v = inf.readLong(1, n) - 1;
        inf.readEoln();
        ensure(!uf.same(u, v));
        uf.merge(u, v);
    }
    ensure(uf.size(0) == n);
    inf.readEof();
    return 0;
}