#include<cstdio>

 #include<cstdlib>

 #include<cstring>

 #include<cmath>

 #include<iostream>

 #include<algorithm>

 #define N 20

 using namespace std;

 int l[N],r[N],n;

 void qian(int x)

 {

     if (x==) return;

     printf("%d ",x);

     qian(l[x]);

     qian(r[x]);

 }

 void zhong(int x)

 {

     if (x==) return;

     zhong(l[x]);

     printf("%d ",x);

     zhong(r[x]);

 }

 void hou(int x)

 {

     if (x==) return;

     hou(l[x]);

     hou(r[x]);

     printf("%d ",x);

 }

 int main()

 {

     int i;

     scanf("%d",&n);

     for (i=;i<=n;i++) scanf("%d%d",&l[i],&r[i]);

     qian();

     printf("\n");

     zhong();

     printf("\n");

     hou();

     printf("\n");

     return ;

 }