#include <bits/stdc++.h>
using namespace std;
int n, m, vis[404040], V, VV, kk;
pair<int, int> rr[404040];
vector<int> v[404040], vv[404040], xx;
map<pair<int, int>, int> xh;
void dfs(int x, int y) {
  if (vis[x] == 2) {
    return;
  }
  if (y != 0) {
    vv[x].push_back(y);
  }
  if (vis[x] == 1) {
    return;
  }
  vis[x] = 1;
  for (int i = 0; i < v[x].size(); i++) {
    int z = v[x][i];
    if (z == y) {
      continue;
    }
    dfs(z, x);
  }
  vis[x] = 2;
  xx.push_back(x);
}
void dfs1(int x) {
  if (vis[x] == 0) {
    return;
  }
  vis[x] = 0;
  kk++;
  for (int i = 0; i < vv[x].size(); i++) {
    int y = vv[x][i];
    dfs1(y);
  }
}
void dfs2(int x, int y) {
  if (vis[x] == 2) {
    return;
  }
  rr[xh[make_pair(x, y)]] = make_pair(x, y);
  if (vis[x] == 1) {
    return;
  }
  vis[x] = 1;
  for (int i = 0; i < v[x].size(); i++) {
    int z = v[x][i];
    if (z == y) {
      continue;
    }
    dfs2(z, x);
  }
  vis[x] = 2;
}
int main() {
  cin >> n >> m;
  for (int i = 0; i < m; i++) {
    int x, y;
    cin >> x >> y;
    v[x].push_back(y);
    v[y].push_back(x);
    xh[make_pair(x, y)] = i;
    xh[make_pair(y, x)] = i;
    rr[i] = make_pair(x, y);
  }
  dfs(1, 0);
  for (int i = xx.size() - 1; i >= 0; i--) {
    kk = 0;
    dfs1(xx[i]);
    if (kk > V) {
      VV = xx[i];
      V = kk;
    }
  }
  cout << V << endl;
  xh[make_pair(0, VV)] = m;
  xh[make_pair(VV, 0)] = m;
  dfs2(VV, 0);
  for (int i = 0; i < m; i++) {
    cout << rr[i].first << ' ' << rr[i].second << endl;
  }
  return 0;
}
