#include<bits/stdc++.h>
 
using namespace std;
 
vector<vector<int> > adj(100);
 
map<int , bool> mp;
 
void print(int node , vector<int> &path){
    path.push_back(node);
    if(adj[node].size() == 0 && mp[node] == false){
        mp[node] = true;
        for(int  i : path) cout << i << " ";
        cout << endl;
    }else{
        for(int i : adj[node]){
            print(i , path);
        }
    }
    path.pop_back();
}
 
 
void solve(){
    vector<int> path;
    print(1 , path);
}
 
 
int main(){
    int n; cin >> n;
    for(int  i = 0; i < n; i++){
        int a,b; cin >> a >> b;
        adj[a].push_back(b);
    }
    solve();
    return 0;
}

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