#include <bits/stdc++.h>
using namespace std;
inline int64_t readli() {
  register char c;
  for (c = getchar(); !(c >= '0' && c <= '9'); c = getchar())
    ;
  register int64_t a = c - '0';
  for (c = getchar(); c >= '0' && c <= '9'; c = getchar())
    a = (a << 3) + (a << 1) + c - '0';
  return a;
}
const int N = 400001;
vector<pair<int, int>> g[N];
vector<int> tg[N];
bool v[N], vc[N];
int low[N], dt[N], p[N], c[N], Time;
pair<int, int> ans[N];
void remABs(int node) {
  v[node] = true;
  low[node] = dt[node] = Time++;
  for (auto &it : g[node]) {
    if (!v[it.first]) {
      p[it.first] = node;
      remABs(it.first);
      low[node] = min(low[node], low[it.first]);
      if (p[node] and low[it.first] <= dt[node]) {
        tg[it.first].push_back(node);
        tg[node].push_back(it.first);
      }
    } else if (it.first != p[node]) {
      low[node] = min(low[node], dt[it.first]);
      tg[it.first].push_back(node);
      tg[node].push_back(it.first);
    }
  }
}
int cc(int node) {
  int ret = 1;
  vc[node] = true;
  for (auto &it : tg[node])
    if (!vc[it]) ret += cc(it);
  return ret;
}
void cg(int node) {
  c[node] = 1;
  for (auto &it : g[node]) {
    if (p[node] != it.first and c[it.first] != 2) {
      ans[it.second] = make_pair(it.first, node);
      if (c[it.first] == 0) {
        p[it.first] = node;
        cg(it.first);
      }
    }
  }
  c[node] = 2;
}
int main() {
  int n = readli();
  int m = readli();
  for (int i = 0; i < m; i++) {
    int a = readli();
    int b = readli();
    g[a].push_back(make_pair(b, i));
    g[b].push_back(make_pair(a, i));
  }
  remABs(1);
  int ans = 0, an;
  for (int i = 1; i <= n; i++) {
    if (vc[i]) continue;
    int tmp = cc(i);
    if (tmp > ans) {
      ans = tmp;
      an = i;
    }
  }
  p[an] = 0;
  cg(an);
  cout << ans << endl;
  for (int i = 0; i < m; i++)
    cout << ::ans[i].first << ' ' << ::ans[i].second << endl;
  return 0;
}
