#include<stdio.h>
int heap[20][2];
void before_traverse(int a)
{
if(!a)
return;
printf("%d ",a);
before_traverse(heap[a][1]);
before_traverse(heap[a][2]);
}
void middle_traverse(int a)
{
if(!a) return;
middle_traverse(heap[a][1]);
printf("%d ",a);
middle_traverse(heap[a][2]);
}
void after_traverse(int a)
{
if(!a) return;
after_traverse(heap[a][1]);
after_traverse(heap[a][2]);
printf("%d ",a);
}
int main()
{
int n,i,j;
scanf("%d",&n);
heap[0][1]=1;
for(i=1;i<=n;i++)
{
scanf("%d%d",&heap[i][1],&heap[i][2]);
}
before_traverse(heap[0][1]);
printf("\n");
middle_traverse(heap[0][1]);
printf("\n");
after_traverse(heap[0][1]);
printf("\n");
return 0;
}