#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <algorithm>
#include <cmath>
#include <stack>
#include <queue>
#include <vector>
#include <map>
#include <string>
#include <iostream>
using namespace std;

const int N = 2010, M = N * N;

// 声明结构体
struct Node {
    int a, b, c;
    bool const operator<(const Node &t) const {
        return c > t.c;
    }
} g[N];

int st[M];      // 某条边是不是访问过，无向图一般用于处理成对就换的边
int d[N];       // 度
int res[M], rl; // 路径数组
int m;          // m条边

// 链式前向星
int e[M], h[N], idx, w[M], ne[M];
void add(int a, int b, int c = 0) {
    e[idx] = b, ne[idx] = h[a], w[idx] = c, h[a] = idx++;
}

void dfs(int u) {
    for (int i = h[u]; ~i; i = h[u]) { // 删边优化
        h[u] = ne[i];
        if (st[i]) continue;
        st[i] = st[i ^ 1] = 1; // 成对变换
        dfs(e[i]);
        // 记录路径
        res[++rl] = w[i];
    }
}
int main() {
#ifndef ONLINE_JUDGE
    freopen("POJ1041.in", "r", stdin);
#endif
    int a, b, c;

    while (true) {
        memset(d, 0, sizeof d);
        memset(st, 0, sizeof st);
        memset(h, -1, sizeof h);
        memset(res, 0, sizeof res);
        idx = rl = m = 0;

        // 本题的输入挺奇怪的，需要使用while(true)+do while的方式来读取最方便
        scanf("%d%d", &a, &b);
        if (a == 0 && b == 0) exit(0);

        do {
            scanf("%d", &c);
            g[m].a = a, g[m].b = b, g[m++].c = c;
            scanf("%d%d", &a, &b);
        } while (a && b);

        // 针对边的边号进行由小到大排序
        sort(g, g + m);

        for (int i = 0; i < m; i++) {
            int a = g[i].a, b = g[i].b, c = g[i].c;
            add(a, b, c), add(b, a, c);
            d[a]++, d[b]++;
        }

        int flag = 0;
        for (int i = 0; i < m; i++) {
            int a = g[i].a, b = g[i].b;
            if ((d[a] & 1) || (d[b] & 1)) {
                flag = 1;
                break;
            }
        }
        if (!flag) {
            dfs(1);
            // 逆序输出序列
            for (int i = rl; i; i--) printf("%d ", res[i]);
        } else
            cout << "Round trip does not exist.";
        puts("");
    }
    return 0;
}