#include <bits/stdc++.h>
using namespace std;
const int MAXN = 6000;
int availability[MAXN][MAXN];
bool used[MAXN];
vector<int> g[MAXN];
int for_dfs[MAXN];
vector<pair<int, int>> for_del;
void dfs(int v) {
  for_dfs[v] = 1;
  for (int i = 0; i < (int)g[v].size();) {
    if (for_dfs[g[v][i]] == 1)
      i++;
    else {
      if (for_dfs[g[v][i]] == 0) dfs(g[v][i]);
      for_del.emplace_back(v, g[v][i]);
      g[v].erase(g[v].begin() + i);
    }
  }
  for_dfs[v] = 2;
}
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  int n, m;
  cin >> n >> m;
  vector<pair<int, int>> edges;
  for (int i = 0; i < m; i++) {
    int v, u;
    cin >> v >> u;
    g[v].push_back(u);
    edges.emplace_back(v, u);
  }
  int c = 1;
  int added = 0;
  vector<int> ans(m);
  while (added < m) {
    memset(for_dfs, 0, sizeof(for_dfs));
    for (int i = 1; i <= n; i++) {
      if (!for_dfs[i]) {
        dfs(i);
      }
    }
    for (auto edge : for_del) {
      ans[find(edges.begin(), edges.end(), edge) - edges.begin()] = c;
    }
    added += for_del.size();
    c++;
    for_del.clear();
  }
  cout << *max_element(ans.begin(), ans.end()) << endl;
  assert(*max_element(ans.begin(), ans.end()) <= m);
  for (int i = 0; i < m; i++) {
    cout << ans[i] << " ";
  }
  return 0;
}
