#include <cstdio>

#include <cstring>

#include <iostream>

using namespace std;

const int N =  , M = N * N;

struct Edge {

    int from, to, nxt,cut;

} edge[M];

int dfn[N],low[N],head[N];

int n, m,tot,cnt;

inline void init(){

    tot = cnt = ;

    memset(dfn, , sizeof dfn);

    memset(head, -, sizeof head);

}

inline void add(int u,int v){

    edge[cnt]=(Edge){u,v,head[u],};

    head[u]=cnt++;

}

void Tarjan(int u, int pre){

    dfn[u] = low[u] = ++tot;

    for (int i=head[u];~i;i=edge[i].nxt){

        int v=edge[i].to;

        if (edge[i].cut) continue;    //如果这个边已经被标记了(标记为-1也是被标记过)，则无需改变之前的标记，因为只需要找到一种可行的标记方案即可

        edge[i].cut=;edge[i^].cut=-;     //贪心的将一个方向的边标记

        if (v == pre) continue;

        if (!dfn[v]){

            Tarjan(v, u);

            low[u] = min(low[u], low[v]);

            if (dfn[u] < low[v])edge[i].cut=edge[i^].cut=;

        }

        else low[u] = min(low[u], dfn[v]);

    }

}

inline void Solve(){

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

        if (edge[i].cut==)printf("%d %d\n", edge[i].from, edge[i].to);

    printf("#\n");

}

int main(){

    int ncase=;

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

        printf("%d\n\n",++ncase);

        init();

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

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

            add(u,v);add(v,u);

        }

        Tarjan(, -);

        Solve();

    }

}