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 fst(t) std::get<0>(t)
#define snd(t) std::get<1>(t)
#define thd(t) std::get<2>(t)
#define unless(p) if(!(p))
#define until(p) while(!(p))

using ll = long long;
using P3 = std::tuple<int,int,int>;

const int dx[8] = {-1, 1, 0, 0, -1, -1, 1, 1}, dy[8] = {0, 0, -1, 1, -1, 1, -1, 1};

template <int n>
struct UnionFind{
    UnionFind(){
        for(int i=0;i<n;i++){
            par[i] = i;
            rank[i] = 0;
        }
    }
    void init(){
        for(int i=0;i<n;i++){
            par[i] = i;
            rank[i] = 0;
        }
    }
    int find(int x){
        if(x == par[x])return x;
        return par[x] = find(par[x]);
    }
    bool same(int x, int y){
        return find(x) == find(y);
    }
    void unite(int x, int y){
        x = find(x);
        y = find(y);
        if(x == y){return;}
        
        if(rank[x] > rank[y]){
            par[y] = x;
        }else{
            par[x] = y;
            if(rank[x] == rank[y]){rank[y]++;}
        }
    }
    int rank[n], par[n];
};

UnionFind<20100> uf;

int main(){
    std::cin.tie(nullptr);
    std::ios::sync_with_stdio(false);

    while(true){
        uf.init();
        
        int N, M;
        std::cin >> N >> M;
        if(!N){break;}
    
        vector<P3> packets;
        for(int i=0;i<M;++i){
            int t, s, d;
            std::cin >> t >> s >> d;

            packets.emplace_back(t, s, d);
        }

        sort(packets.begin(), packets.end());

        for(auto &p : packets){
            int s, d;
            tie(ignore, s, d) = p;

            if(uf.same(1, s)){
                uf.unite(s, d);
            }
        }

        int res = 0;
        for(int i=1;i<=N;++i){
            if(uf.same(1, i)){++res;}
        }

        std::cout << res << std::endl;
    }
}

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) {
    a = root(a), b = root(b);
    if (a == b) return;
    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;
  }
}

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])f[e.to]=true,ans++;
    }
    cout<<ans<<endl;
  }
}

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

using namespace std;

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

struct st {
    int t, s, d;
};
bool b[20005];
st p[20005];

int main() {
    int n, m;
    while (scanf("%d%d", &n, &m), n) {
        rep(i, m) {
            int t, s, d; scanf("%d%d%d", &t, &s, &d);
            p[i] = {t, s, d};
        }
        sort(p, p + m, [](st a, st b){return a.t < b.t;});
        memset(b, 0, sizeof(b));
        b[1] = 1;
        rep(i, m)b[p[i].d] |= b[p[i].s];
        printf("%d\n", count(b, b+n+1, 1));
    }
}