#include <bits/stdc++.h>
using namespace std;

void executeTime() {
    cerr << "Time Taken: " << (float)clock() / CLOCKS_PER_SEC << " secs";
}

int main() {

    int n; cin >> n;

    vector<vector<int>> mp(n + 1);

    for (int i = 0; i < n - 1; i++) {
        int u, v; cin >> u >> v;

        mp[u].push_back(v);
        mp[v].push_back(u);
    }


    function<int(int, int)> solve = [&](int src, int p) {

        int cnt = 0;

        for (auto &v : mp[src]) {
            if (v == p) {
                cnt++;
                continue;
            };

            int ans = solve(v, src);
            if (ans != -1) return ans;

            cnt += 1;
        }

        if (cnt < 3) return src;

        return -1;
    };

    int ans = solve(1, -1);

    cout << ans << endl;

    executeTime();
    return 0;
}