#include <iostream>
#include <algorithm>
#include <vector>
#include <map>

using namespace std;

vector<int> g[100000];
int dp[100000];
int ans[100000];

int mex(const map<int, int> &mp) {
    int res = 0;
    while (mp.count(res)) res++;
    return res;
}

void dfs(int u, int p) {
    map<int, int> mp;
    for (int v : g[u]) if (v != p) {
        dfs(v, u);
        mp[dp[v]]++;
    }
    dp[u] = mex(mp);
}

void dfs2(int u, int p) {
    map<int, int> mp;
    for (int v : g[u]) {
        mp[dp[v]]++;
    }
    ans[u] = mex(mp);
    for (int v : g[u]) if (v != p) {
        if (mp[dp[v]] == 1 && dp[v] < ans[u]) {
            dp[u] = dp[v];
        }
        dfs2(v, u);
    }
}

int main() {
	int n;
	cin >> n;
	for (int i = 0; i < n - 1; i++) {
        int u, v;
        cin >> u >> v;
		u--;
		v--;
		g[u].push_back(v);
		g[v].push_back(u);
	}
    dfs(0, -1);
    dfs2(0, -1);
    cout << count(ans, ans + n, 0) << endl;
    for (int i = 0; i < n; i++) {
        if (ans[i] == 0) {
            cout << i + 1 << endl;
        }
    }
}