#include<iostream>

#include<cstdio>

#include<cstring>

using namespace std;

int const maxn=4e5+;

int n,m,hd[maxn],ct=,cnt=,dfn[maxn],low[maxn],tim,col[maxn],cr,siz[maxn];

int sta[maxn],top,head[maxn];

bool vis[maxn];

//struct N{

//    int to,nxt,bh,u,v,f;

//    N(int t=0,int n=0,int b=0):to(t),nxt(n),bh(b) {}

//}ed[maxn<<1],e[maxn],edge[maxn<<1];//这样写会爆空间？！

struct N{

    int to,nxt,bh;

    N(int t=,int n=,int b=):to(t),nxt(n),bh(b) {}

}ed[maxn<<],edge[maxn<<];

struct E{int u,v,f;}e[maxn];

void add(int x,int y,int b){ed[++ct]=N(y,hd[x],b); hd[x]=ct;}

void add2(int x,int y,int b){edge[++cnt]=N(y,head[x],b); head[x]=cnt;}

void tarjan(int x,int f)

{

    dfn[x]=low[x]=++tim; vis[x]=; sta[++top]=x;

    for(int i=hd[x];i;i=ed[i].nxt)

    {

        int u=ed[i].to;

        if(u==f)continue;

        if(!dfn[u]) tarjan(u,x),low[x]=min(low[x],low[u]);

        else if(vis[u]) low[x]=min(low[x],dfn[u]);

    }

    if(dfn[x]==low[x])

    {

        cr++;

        while(sta[top]!=x)

        {

            int y=sta[top]; top--;

            vis[y]=; col[y]=cr; siz[cr]++;

        }

        top--; vis[x]=; col[x]=cr; siz[cr]++;

    }

}

void dfs(int x)

{

    vis[x]=;

    for(int i=head[x],u,eg;i;i=edge[i].nxt)

    {

        if(vis[u=edge[i].to])continue;

        if(x==col[e[eg=edge[i].bh].u]) e[eg].f=;

        else e[eg].f=;

        dfs(u);

    }

}

void dfs2(int x)

{

    vis[x]=;

    for(int i=hd[x],u,eg;i;i=ed[i].nxt)

    {

        u=ed[i].to;

        if(col[u]!=col[x])continue;

        if(x==e[eg=ed[i].bh].u) e[eg].f=;

        else e[eg].f=;

        if(!vis[u])dfs2(u);

    }

}

int main()

{

    scanf("%d%d",&n,&m);

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

    {

        scanf("%d%d",&e[i].u,&e[i].v);

        add(e[i].u,e[i].v,i); add(e[i].v,e[i].u,i);

    }

    for(int i=;i<=n;i++) if(!dfn[i])tarjan(i,);

    memset(vis,,sizeof vis);

    for(int i=;i<=n;i++) if(!vis[i])dfs2(i);

    for(int i=,u,v;i<=ct;i++)

        if((u=col[ed[i].to])!=(v=col[ed[i^].to]))add2(u,v,ed[i].bh),add2(v,u,ed[i].bh);

    int rt=,mx=;

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

        if(siz[i]>mx)mx=siz[i],rt=i;

    printf("%d\n",mx);

    memset(vis,,sizeof vis);

    dfs(rt);

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

    {

        if(e[i].f==)printf("%d %d\n",e[i].u,e[i].v);

        else printf("%d %d\n",e[i].v,e[i].u);

    }

    return ;

}