#include <iostream>
#include <fstream>
#include <string>
#include <vector>
#include <set>
#include <map>
#include <algorithm>
#include <queue>
#include <iomanip>
#include <cassert>
#include <cmath>
#include <stack>

using namespace std;

using ll = long long;
using ull = unsigned long long;

const int DIM = 5e5 + 5;
const ll INF = 1e18;

bool cyc[DIM];
int viz[DIM];
int nr;
int low[DIM], lim[DIM];
int wh[DIM];
vector<pair<int, int>> v[DIM];
vector<pair<int, int>> vt[DIM];
vector<vector<int>> ctc;
stack<int> st;

void dfs(int nod) {
  viz[nod] = 1;
  low[nod] = lim[nod] = ++nr;
  st.push(nod);

  for (auto it : v[nod]) {
    if (!viz[it.first]) {
      dfs(it.first);
      low[nod] = min(low[nod], low[it.first]);
    } else if (viz[it.first] == 1) {
      low[nod] = min(low[nod], lim[it.first]);
    }
  }

  if (low[nod] == lim[nod]) {
    ctc.emplace_back();
    int x;
    do {
      x = st.top();
      st.pop();

      viz[x] = 2;
      wh[x] = ctc.size();
      ctc.back().push_back(x);
    } while (x != nod);
  }
}

void dfs2(int nod) {
  viz[nod] = 3;
  for (auto it : v[nod]) {
    if (viz[it.first] < 3) {
      dfs2(it.first);
    }
    cyc[nod] |= cyc[it.first];
  }
  viz[nod] = 4;
}

int f[DIM];
ll sum[DIM];

bool dfs3(int nod) {
  f[nod] = 1;
  for (auto it : vt[nod]) {
    if (wh[it.first] != wh[nod])
      continue;

    if (f[it.first]) {
      if (sum[it.first] != sum[nod] + it.second)
        return true;
    } else {
      sum[it.first] = sum[nod] + it.second;
      bool r = dfs3(it.first);
      if (r)
        return true;
    }
  }

  f[nod] = 2;
  return false;
}

void solve() {
  int n, m, q;
  cin >> n >> m;
  //cin >> n >> m >> q;

  for (int i = 1; i <= m; ++i) {
    int a, b, x, y;
    cin >> a >> b;
    a--, b--;
    v[a].push_back({b, 1});
    continue;
    if (b == 0)
      continue;
    x = (a % n + n) % n;
    y = ((a + b) % n + n) % n;

    v[x].push_back({y, b});
    vt[x].push_back({y, b});
    vt[y].push_back({x, -b});
  }

  for (int i = 0; i < n; ++i) {
    if (!viz[i]) {
      dfs(i);
    }
  }

  for (int i = 0; i < n; ++i) {
    assert(viz[i] == 2);
  }

    cout << ctc.size() << '\n';
  for (auto &c : ctc) {
      for (auto nod : c) {
        cout << nod + 1<< ' ';
      }
      cout << '\n';
  }
  return;

  for (int i = 0; i < n; ++i) {
    if (viz[i] < 3)
      dfs2(i);
  }

  for (int i = 0; i < n; ++i) {
    assert(viz[i] == 4);
  }

  for (int i = 1; i <= q; ++i) {
    int x;
    cin >> x;
    x = (x % n + n) % n;
    if (cyc[x]) {
      cout << "Yes\n";
    } else {
      cout << "No\n";
    }
  }
}

signed main() {
#ifdef LOCAL
    freopen("test.in", "r", stdin);
    freopen("test.out", "w", stdout);
#else
    freopen("ctc.in", "r", stdin);
    freopen("ctc.out", "w", stdout);
#endif // LOCAL
    ios_base::sync_with_stdio(false);
    cin.tie(0);
    int nrt = 1;
    //cin >> nrt;
    for (int t = 1; t <= nrt; t++) {
        solve();
    }
    return 0;
}