Go: package main

import (
	"bufio"
	"fmt"
	"os"
	"sort"
	"strconv"
	"strings"
)

func main() {
	io := NewIo()
	defer io.Flush()
	for {
		n, m := io.NextInt(), io.NextInt()
		if n == 0 {
			break
		}
		dat := make([]Dat, m)
		for i := 0; i < m; i++ {
			dat[i] = Dat{io.NextInt(), io.NextInt(), io.NextInt()}
		}
		sort.Slice(dat, func(i, j int) bool { return dat[i].t < dat[j].t })
		infected := make([]bool, n+1)
		infected[1] = true
		for i := 0; i < m; i++ {
			infected[dat[i].d] = infected[dat[i].d] || infected[dat[i].s]
		}
		cnt := 0
		for i := 0; i <= n; i++ {
			if infected[i] {
				cnt++
			}
		}
		io.Println(cnt)
	}
}

type Dat struct {
	t, s, d int
}

// I/O template
type Io struct {
	reader    *bufio.Reader
	writer    *bufio.Writer
	tokens    []string
	nextToken int
}

func NewIo() *Io {
	return &Io{
		reader: bufio.NewReader(os.Stdin),
		writer: bufio.NewWriter(os.Stdout),
	}
}

func (io *Io) Flush() {
	err := io.writer.Flush()
	if err != nil {
		panic(err)
	}
}

func (io *Io) NextLine() string {
	var buff []byte
	for {
		line, isPrefix, err := io.reader.ReadLine()
		if err != nil {
			panic(err)
		}
		buff = append(buff, line...)
		if !isPrefix {
			break
		}
	}
	return string(buff)
}

func (io *Io) Next() string {
	for io.nextToken >= len(io.tokens) {
		line := io.NextLine()
		io.tokens = strings.Fields(line)
		io.nextToken = 0
	}
	s := io.tokens[io.nextToken]
	io.nextToken++
	return s
}

func (io *Io) NextInt() int {
	i, err := strconv.Atoi(io.Next())
	if err != nil {
		panic(err)
	}
	return i
}

func (io *Io) NextFloat() float64 {
	i, err := strconv.ParseFloat(io.Next(), 64)
	if err != nil {
		panic(err)
	}
	return i
}

func (io *Io) Println(a ...interface{}) {
	fmt.Fprintln(io.writer, a...)
}

func (io *Io) Printf(format string, a ...interface{}) {
	fmt.Fprintf(io.writer, format, a...)
}

func (io *Io) PrintIntSlice(a []int) {
	b := make([]interface{}, 0, len(a))
	for _, x := range a {
		b = append(b, x)
	}
	io.Println(b...)
}

func (io *Io) PrintStringSlice(a []string) {
	b := make([]interface{}, 0, len(a))
	for _, x := range a {
		b = append(b, x)
	}
	io.Println(b...)
}

func Log(name string, value interface{}) {
	fmt.Fprintf(os.Stderr, "%s=%+v\n", name, value)
}

func ExampleIo() {
	io := NewIo()
	defer io.Flush()
	a := make([]int, 0, 3)
	a[0], a[1], a[2] = io.NextInt(), io.NextInt(), io.NextInt()
	io.Println(a)
	io.PrintIntSlice(a)
	Log("io", a)
}

C++: #include <bits/stdc++.h>

using namespace std;

#define REP(i,a,b) for(int i=a;i<(int)b;i++)
#define rep(i,n) REP(i,0,n)

struct state {
  int t, s, d;
};
bool cmp(state const& lhs, state const& rhs) {
  return lhs.t < rhs.t;
}

int main() {
  
  int N, M;
  while(cin >> N >> M && (N|M)) {
    vector<state> v;
    rep(i, M) {
      int t, s, d; cin >> t >> s >> d; s--, d--;
      v.push_back((state){t, s, d});
    }
    sort(v.begin(), v.end(), cmp);
    vector<bool> g(N);
    g[0] = 1;
    rep(i, M) {
      g[v[i].d] = g[v[i].d] || g[v[i].s];
    }
    int ans = 0;
    rep(i, N) {
      if(g[i]) { ans++; }
    }
    cout << ans << endl;
  }

  return 0;
}

C++: #include<iostream>
#include<cstdio>
#include<algorithm>
#include<vector>
using namespace std;

struct edge{
  int from,to,cost;
  bool operator < (const edge &p)const{    return cost < p.cost;  }
};

int N,M,a,b,c;
bool f[20001];
vector<edge> g;

int main(){
  while(1){
    cin>>N>>M;
    if(N==0&&M==0)break;
    g.clear();
    for(int i=1;i<=N;i++)f[i]=false;
    f[1]=true;
    for(int i=0;i<M;i++){
      scanf("%d %d %d",&a,&b,&c);
      g.push_back((edge){b,c,a});
    }
    sort(g.begin(),g.end());
    int ans=1;
    for(int i=0;i<M;i++){
      edge e=g[i];
      if(f[e.from]){
	if(!f[e.to])ans++;
	f[e.to]=true;
      }
    }
    cout<<ans<<endl;
  }
}

C++: #include <bits/stdc++.h>
#define r(i,n) for(int i=0;i<n;i++)
using namespace std;
int main(){
	long long n,m;
	while(cin>>n>>m,n){
		long long a[20001]={0},b[1000000000][2]={0},t,s=0;
		a[1]=1;
		r(i,m){
			cin>>t;
			cin>>b[t][0]>>b[t][1];
		}
		r(i,1000000000)if(a[b[i][0]])a[b[i][1]]=1;
		r(i,1000000000)if(a[i])s++;
		cout<<s<<endl;
	}
}

C++: #include<bits/stdc++.h>
using namespace std;

#define FOR(i,a,b) for (int i=(a);i<(b);i++)
#define RFOR(i,a,b) for (int i=(b)-1;i>=(a);i--)
#define REP(i,n) for (int i=0;i<(n);i++)
#define RREP(i,n) for (int i=(n)-1;i>=0;i--)
#define ALL(a) (a).begin(),(a).end()
#define DEBUG(a) "(" << #a << ": " << (a) << ")"

template<typename T>
void chmin(T &x, T y) { x = min(x, y); }

template<typename T>
void chmax(T &x, T y) { x = max(x, y); }

typedef long long int lli;
typedef long double ld;
typedef tuple<int,int,int> Tr;

const int INF = INT_MAX/2 - 1;
const double EPS = 1e-14;
const int dx[4] = {0, 1, 0, -1}; // {-1,  0,  1, -1, 1, -1, 0, 1};
const int dy[4] = {1, 0, -1, 0}; // {-1, -1, -1,  0, 0,  1, 1, 1};

int main() {
  cout << fixed << setprecision(10);
  int N, M;
  while (cin >> N >> M and N) {
    vector<Tr> data;
    REP(i, M) {
      int t, s, d;
      cin >> t >> s >> d;
      data.emplace_back(t, --s, --d);
    }
    sort(ALL(data));
    vector<bool> infected(N);
    infected[0] = true;
    for (Tr datum : data) {
      int s, d;
      tie(ignore, s, d) = datum;
      if (infected[s]) infected[d] = true;
    }
    int ans = 0;
    for (bool b:infected) if (b) ans++;
    cout << ans << endl;

  }
  return 0;
}

C++: // clang-format off
#include <bits/stdc++.h>
#define int long long
#define main signed main()
// #define main int main()
#define loop(i, a, n) for (int i = (a); i < (n); i++)
#define rep(i, n) loop(i, 0, n)
#define all(v) (v).begin(), (v).end()
#define rall(v) (v).rbegin(), (v).rend()
#define prec(n) fixed << setprecision(n)
#define stlice(from, to) substr(from, (to) - (from) + 1)
#define pb push_back
#define mp make_pair
#define mt make_tuple
#define fi first
#define se second
using namespace std;
using pii = pair<int, int>;
using vi = vector<int>;
using vd = vector<double>;
using vc = vector<char>;
using vb = vector<bool>;
using vs = vector<string>;
using vpii = vector<pii>;
using vvi = vector<vi>;
using vvb = vector<vb>;
using vvpii = vector<vpii>;
template<typename A> using fn = function<A>;
constexpr int INF = sizeof(int) == sizeof(long long) ? 1000000000000000000LL : 1000000000;
constexpr int MOD = 1000000007;
constexpr double PI = acos(-1);
template<typename A, typename B> bool cmin(A &a, const B &b) { return a > b ? (a = b, true) : false; }
template<typename A, typename B> bool cmax(A &a, const B &b) { return a < b ? (a = b, true) : false; }
constexpr bool odd(const int &n) { return n & 1; }
constexpr bool even(const int &n) { return !odd(n); }
void solve();
main { solve(); return 0; }
// clang-format on

class UFT {
private:
  vi data, rnk;

public:
  UFT(const int &size)
    : data(size), rnk(size) {
    iota(all(data), 0);
  }

  int root(const int &x) {
    return x;
  }

  bool same(const int &a, const int &b) {
    return root(a) == root(b);
  }

  void unite(int a, int b) {
    data[b] = a;
  }
};

void solve() {
  int n, m;
  while (cin >> n >> m, n) {
    vector<tuple<int, int, int>> v;
    while (m--) {
      int t, s, d;
      cin >> t >> s >> d;
      v.emplace_back(t, --s, --d);
    }
    sort(all(v));
    UFT uf(n);
    rep(i, v.size()) {
      int s, d;
      tie(ignore, s, d) = v[i];
      if (uf.same(0, s)) uf.unite(0, d);
    }
    int c = 0;
    rep(i, n) c += uf.same(0, i);
    cout << c << endl;
  }
}