#include <bits/stdc++.h>

using namespace std;
const int N = 1e6 + 10;
//树的结构体+存储数组
struct Node {
    int id;   // 当前结点ID
    int left; // 左结点ID
    int right;// 右结点ID
} t[N];
int n;

/**
测试用例：
7
2 7
3 6
4 5
0 0
0 0
0 0
0 0
 */
//前序遍历
void pre_order(int x) {
    printf("%d ", x);
    if (t[x].left) pre_order(t[x].left);
    if (t[x].right) pre_order(t[x].right);
}

//中序遍历
void in_order(int x) {
    if (t[x].left) in_order(t[x].left);
    printf("%d ", x);
    if (t[x].right) in_order(t[x].right);
}

//后序遍历
void post_order(int x) {
    if (t[x].left) post_order(t[x].left);
    if (t[x].right) post_order(t[x].right);
    printf("%d ", x);
}

int main() {
    cin >> n;
    //创建二叉树 build
    for (int i = 1; i <= n; i++) cin >> t[i].left >> t[i].right, t[i].id = i;
    //前序
    pre_order(1);
    printf("\n");
    //中序
    in_order(1);
    printf("\n");
    //后序
    post_order(1);
    printf("\n");
    return 0;
}