#include <stdio.h>
#include <string.h>
#include <algorithm>
#include <iostream>
#include <math.h>
#include <assert.h>
#include <vector>
#include <queue>
#include <string>
#include <map>
#include <set>

using namespace std;
typedef long long ll;
typedef unsigned int uint;
typedef unsigned long long ull;
static const double EPS = 1e-9;
static const double PI = acos(-1.0);

#define REP(i, n) for (int i = 0; i < (int)(n); i++)
#define FOR(i, s, n) for (int i = (s); i < (int)(n); i++)
#define FOREQ(i, s, n) for (int i = (s); i <= (int)(n); i++)
#define FORIT(it, c) for (__typeof((c).begin())it = (c).begin(); it != (c).end(); it++)
#define MEMSET(v, h) memset((v), h, sizeof(v))

typedef int Weight;
struct Edge {
  int src;
  int dest;
  Weight weight;
  Edge(int src, int dest, Weight weight) : src(src), dest(dest), weight(weight) {;}
  bool operator<(const Edge &rhs) const {
    if (weight != rhs.weight) { return weight > rhs.weight; }
    if (src != rhs.src) { return src < rhs.src; }
    return dest < rhs.dest;
  }
};
typedef vector<Edge> Edges;
typedef vector<Edges> Graph;
typedef vector<Weight> Array;
typedef vector<Array> Matrix;

void PrintMatrix(const Matrix &matrix) {
  for (int y = 0; y < (int)matrix.size(); y++) {
    for (int x = 0; x < (int)matrix[y].size(); x++) {
      printf("%d ", matrix[y][x]);
    }
    puts("");
  }
}


void SccDfs(const Graph &g, int from, vector<int> &visit, vector<int> &st) {
  visit[from] = 1;
  for (Edges::const_iterator it = g[from].begin(); it != g[from].end(); it++) {
    if (visit[it->dest]) { continue; }
    SccDfs(g, it->dest, visit, st);
  }
  st.push_back(from);
}

vector<vector<int> > Scc(const Graph &g) {
  const int n = g.size();
  vector<vector<int> > ret;
  Graph revg(n);
  for (int i = 0; i < n; i++) {
    for (Edges::const_iterator it = g[i].begin(); it != g[i].end(); it++) {
      revg[it->dest].push_back(Edge(it->dest, i, it->weight));
    }
  }
  vector<int> st;
  vector<int> visit(n, 0);
  for (int i = 0; i < n; i++) {
    if (visit[i]) { continue; }
    SccDfs(g, i, visit, st);
  }
  visit = vector<int>(n, 0);
  for (int i = n - 1; i >= 0; i--) {
    int index = st[i];
    if (visit[index]) { continue; }
    vector<int> nret;
    SccDfs(revg, index, visit, nret);
    ret.push_back(nret);
  }
  return ret;
}

int group[10000];
Graph g;
int main() {
  int n, m;
  while (scanf("%d %d", &n, &m) > 0 && n > 0) {
    g = Graph(n);
    REP(i, m) {
      int from, to;
      scanf("%d %d", &from, &to);
      from--;
      to--;
      g[from].push_back(Edge(from, to, 0));
    }
    int ans = 0;
    vector<vector<int> > scc = Scc(g);
    REP(i, scc.size()) {
      FORIT(it, scc[i]) { group[*it] = i; }
    }
    FORIT(it1, scc) {
      if (it1->size() == 1) { continue; }
      ans += 1 - it1->size();
      FORIT(it2, *it1) {
        int from = *it2;
        FORIT(it3, g[from]) {
          int to = it3->dest;
          ans += group[from] == group[to];
        }
      }
    }
    printf("%d\n", ans);
  }
}