#include<iostream>
#include<cstdio>
#include<cstring>
using namespace std;
const int N=4e5+5;
int n,m,cnt,col[N],hd[N],xnt=1,thd[N],txnt,siz[N];
int sta[N],top,low[N],dfn[N],tim;
bool vis[N],ins[N];
struct Ed{int tnxt,nxt,fr,to;bool use;Ed(int n=0,int f=0,int t=0):nxt(n),fr(f),to(t) {use=0;}//!!!use=0!!!
}ed[N<<1];
void add(int x,int y)
{ed[++xnt]=Ed(hd[x],x,y);hd[x]=xnt;ed[++xnt]=Ed(hd[y],y,x);hd[y]=xnt;
}
void tarjan(int cr,int fa)
{dfn[cr]=low[cr]=++tim;sta[++top]=cr;ins[cr]=1;for(int i=hd[cr],v;i;i=ed[i].nxt)if(ins[v=ed[i].to]&&v!=fa)low[cr]=min(low[cr],dfn[v]);else if(!dfn[v])tarjan(v,cr),low[cr]=min(low[cr],low[v]);if(dfn[cr]==low[cr]){cnt++;while(sta[top]!=cr)col[sta[top]]=cnt,ins[sta[top--]]=0,siz[cnt]++;top--;col[cr]=cnt;ins[cr]=0;siz[cnt]++;}
}
void dfsx(int cr,int fa)
{for(int i=thd[cr];i;i=ed[i].tnxt){if(col[ed[i].to]!=fa)ed[i^1].use=1,dfsx(col[ed[i].to],cr);}
}
void dfs(int cr,int fa)
{vis[cr]=1;for(int i=hd[cr],v;i;i=ed[i].nxt){if(col[v=ed[i].to]!=col[cr]||v==fa)continue;if(!ed[i^1].use)ed[i].use=1;//!if(!vis[v])dfs(v,cr);//!vis[v]!!
    }
}
int main()
{scanf("%d%d",&n,&m);int x,y;for(int i=1;i<=m;i++){scanf("%d%d",&x,&y);add(x,y);}tarjan(1,0);for(int i=2,u,v;i<=xnt;i++)if((u=col[ed[i].fr])!=(v=col[ed[i].to]))ed[i].tnxt=thd[u],thd[u]=i;int mx=0,k;for(int i=1;i<=cnt;i++)if(siz[i]>mx)mx=siz[i],k=i;printf("%d\n",mx);dfsx(k,0);for(int i=1;i<=n;i++)if(!vis[i])dfs(i,0);for(int i=2;i<=xnt;i+=2)if(ed[i].use)printf("%d %d\n",ed[i].fr,ed[i].to);else printf("%d %d\n",ed[i].to,ed[i].fr);return 0;
}