#include <iostream>

#include <cstdio>

#include <sstream>

#include <cstring>

#include <map>

#include <set>

#include <vector>

#include <stack>

#include <queue>

#include <algorithm>

#include <cmath>

#define MOD 2018

#define LL long long

#define ULL unsigned long long

#define maxn 100009

#define Pair pair<int, int>

#define mem(a, b) memset(a, b, sizeof(a))

#define _  ios_base::sync_with_stdio(0),cin.tie(0)

//freopen("1.txt", "r", stdin);

using namespace std;

const int INF = 0x3f3f3f3f;

int head[maxn], d[maxn], cur[maxn], vis[maxn];

int n, m, s, t;

int cnt = ;

struct node{

    int u, v, c, next;

}Node[maxn*];

void add_(int u, int v, int c)

{

    Node[cnt].u = u;

    Node[cnt].v = v;

    Node[cnt].c = c;

    Node[cnt].next = head[u];

    head[u] = cnt++;

}

void add(int u, int v, int c)

{

    add_(u, v, c);

    add_(v, u, c);

}

bool bfs()

{

    queue<int> Q;

    mem(d,);

    Q.push(s);

    d[s] = ;

    while(!Q.empty())

    {

        int u = Q.front(); Q.pop();

        for(int i=head[u]; i!=-; i=Node[i].next)

        {

            node e = Node[i];

            if(!d[e.v] && e.c > )

            {

                d[e.v] = d[e.u] + ;

                Q.push(e.v);

                if(e.v == t) return ;

            }

        }

    }

    return d[t] != ;

}

int dfs(int u, int cap)

{

    if(u == t || cap == )

        return cap;

    int ret = ;

    for(int &i=cur[u]; i!=-; i=Node[i].next)

    {

        node e = Node[i];

        if(d[e.v] == d[e.u] +  && e.c > )

        {

            int V = dfs(e.v, min(cap, e.c));

            Node[i].c -= V;

            Node[i^].c += V;

            cap -= V;

            ret += V;

            if(cap == ) break;

        }

    }

    return ret;

}

int dinic()

{

    int ans = ;

    while(bfs())

    {

        memcpy(cur, head, sizeof(head));

        ans += dfs(s, INF);

    }

    return ans;

}

void find(int u)

{

    for(int i=head[u]; i!=-; i=Node[i].next)

    {

        node e = Node[i];

        if(vis[e.v] || e.c == ) continue;

        vis[e.v] = ;

        find(e.v);

    }

}

int main()

{

    while(~scanf("%d%d",&n,&m) && n+m)

    {

        mem(vis,);

        mem(head,-);

        cnt = ;

        s = ; t = ;

        for(int i=; i<m; i++)

        {

            int u, v, c;

            scanf("%d%d%d",&u,&v,&c);

            add(u, v, c);

        }

        dinic();

        vis[s] = ;

        find(s);       //寻找能从s到达的路

        for(int i=; i<cnt; i+=)

            if(vis[Node[i].u] && !vis[Node[i].v] || !vis[Node[i].u] && vis[Node[i].v])   // 如果一个能到达 另一个不能到达 则为割边 输出即可

                cout<< Node[i].u << " " << Node[i].v <<endl;

        cout<< endl;

    }

    return ;

}