#include<bits/stdc++.h>
using namespace std;
int a[100][2];
void preorder(int u){
cout<<u<<" ";
if(a[u][0])preorder(a[u][0]);
if(a[u][1])preorder(a[u][1]);
} void preorder1(int u){
if(a[u][0])preorder1(a[u][0]);
cout<<u<<" ";
if(a[u][1])preorder1(a[u][1]);
} void preorder2(int u){
if(a[u][0])preorder2(a[u][0]);
if(a[u][1])preorder2(a[u][1]);
cout<<u<<" ";
} int main(){
int n;
cin>>n;
for(int i=1;i<=n;i++)cin>>a[i][0]>>a[i][1];
preorder(1);
cout<<"\n";
preorder1(1);
cout<<"\n";
preorder2(1);
return 0;
}