#include<cstdio>

#include<cstring>

#include<iostream>

#include<algorithm>

#include<queue>

using namespace std;

#define N 100005

#define INF 0x3fffffff

struct node {int v, flow, next;} a[N<<];

int Layer[N], Head[N], cnt, n, m;

void Init()

{

    cnt = ;

    memset(Head, -, sizeof(Head));

}

void Add(int u, int v, int flow)

{

    a[cnt].v = v;

    a[cnt].flow = flow;

    a[cnt].next = Head[u];

    Head[u] = cnt++;

}

bool BFS(int Start, int End)

{

    queue<int>Q;

    Q.push(Start);

    memset(Layer, , sizeof(Layer));

    Layer[Start] = ;

    while(Q.size())

    {

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

        if(u==End) return true;

        for(int i=Head[u]; i!=-; i=a[i].next)

        {

            int v = a[i].v;

            if(!Layer[v] && a[i].flow)

            {

                Layer[v] = Layer[u] + ;

                Q.push(v);

            }

        }

    }

    return false;

}

int DFS(int u, int MaxFlow, int End)

{

    if(u==End) return MaxFlow;

    int uflow=;

    for(int i=Head[u]; i!=-; i=a[i].next)

    {

        int v = a[i].v;

        if(Layer[v]==Layer[u]+ && a[i].flow)

        {

            int flow = min(a[i].flow, MaxFlow-uflow);

            flow = DFS(v, flow, End);

            a[i].flow -= flow;

            a[i^].flow += flow;

            uflow += flow;

            if(uflow==MaxFlow) break;

        }

    }

    if(uflow==) Layer[u] = ;

    return uflow;

}

void Dinic(int Start, int End)

{

    int MaxFlow = ;

    while(BFS(Start, End)==true)

      MaxFlow += DFS(Start, INF, End);

}

int main()

{

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

    {

        int i, u, v, flow, x[N], y[N];

        Init();

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

        {

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

            x[i] = u, y[i] = v;

            Add(u, v, flow);

            Add(v, u, flow);

        }

        Dinic(, );

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

        {

            if((!Layer[x[i]] && Layer[y[i]]) || (Layer[x[i]] && !Layer[y[i]]))

                printf("%d %d\n", x[i], y[i]);

        }

        printf("\n");

    }

    return ;

}