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 INF_LL (int64)1e18
#define INF (int32)1e9
#define REP(i, n) for(int64 i = 0;i < (n);i++)
#define FOR(i, a, b) for(int64 i = (a);i < (b);i++)
#define all(x) x.begin(),x.end()
#define fs first
#define sc second

using int32 = int_fast32_t;
using uint32 = uint_fast32_t;
using int64 = int_fast64_t;
using uint64 = uint_fast64_t;
using PII = pair<int32, int32>;
using PLL = pair<int64, int64>;

const double eps = 1e-10;

template<typename A, typename B>inline void chmin(A &a, B b){if(a > b) a = b;}
template<typename A, typename B>inline void chmax(A &a, B b){if(a < b) a = b;}

template<typename T>
vector<T> make_v(size_t a){return vector<T>(a);}

template<typename T,typename... Ts>
auto make_v(size_t a,Ts... ts){
  return vector<decltype(make_v<T>(ts...))>(a,make_v<T>(ts...));
}

template<typename T,typename U,typename... V>
typename enable_if<is_same<T, U>::value!=0>::type
fill_v(U &u,const V... v){u=U(v...);}

template<typename T,typename U,typename... V>
typename enable_if<is_same<T, U>::value==0>::type
fill_v(U &u,const V... v){
  for(auto &e:u) fill_v<T>(e,v...);
}

int main(void){
	cin.tie(0);
	ios::sync_with_stdio(false);
	int64 N, M;
	while (cin >> N >> M && N+M) {
		using T = tuple<int64, int64, int64>;
		bool infected[20020] = {};
		int64 res = 1;
		infected[0] = 1;
		vector<T> v(M);
		REP(i, M) {
			int64 a, b, c;
			cin >> a >> b >> c; b--; c--;
			v.push_back(T(a, b, c));
		}
		sort(all(v));
		REP(i, M) {
			int64 a, b, c;
			tie(a, b, c) = v[i];
			if (infected[b] && !infected[c]) {
				res++;
				infected[c] = 1;
			}
		}
		cout << res << endl;
	}
}

C++: #include<iostream>
#include<cstdio>
#include<string>
#include<vector>
#include<cmath>
#include<algorithm>
#include<functional>
#include<iomanip>
#include<queue>
#include<ciso646>
#include<random>
#include<map>
#include<set>
using namespace std;
typedef long long ll;
const ll MOD = 1000000007;
const ll INF = (ll)1000000007 * 1000000007;
const double PI = 3.14159265358979;
const double E = 2.718281828459045;
const double root2 = sqrt(2);
typedef pair<int, int> P;
typedef unsigned int ui;
int main() {
	int n, m;
	while (cin >> n >> m) {
		if (n == 0)break;
		int t, s, d;
		int infe[20001] = {}; infe[1] = 1;
		pair<int,P> p[20000];
		for (int i = 0; i < m; i++) {
			cin >> t >> s >> d;
			p[i].first = t;
			p[i].second.first = s;
			p[i].second.second = d;
		}
		sort(p, p + m);
		for (int i = 0; i < m; i++) {
			if (infe[p[i].second.first]) {
				infe[p[i].second.second] = 1;
			}
		}
		int cnt = 0;
		for (int i = 1; i <= n; i++) {
			if (infe[i])cnt++;
		}
		cout << cnt << endl;
	}
	return 0;
}

C++: #include<iostream>
#include<algorithm>
#include<vector>
using namespace std;
struct pac{
  int t;
  int o;
  int m;
  bool operator<(const pac& right)const{
    return t==right.t ? o<right.o:t < right.t ;
  }
};
int main(){
  while(1){
    int n,x;
    cin >> n >> x;
    if(n==0&&x==0)break;
    vector<pac> p(x);
    vector<int> v(n+1,0);
    int c=1;
    v[1]=1;
    for(int i=0;i<x;i++){
      cin >> p[i].t >> p[i].o >> p[i].m;
    }
    sort(p.begin(),p.end());
    for(int i=0;i<x;i++){
      if(v[p[i].o]==1){v[p[i].m]=1;
	c++;}
    }
    cout << c<< endl; 
  }
  return 0;

}

C++: #include <bits/stdc++.h>
using namespace std;
#define FOR(i, s, n) for(int i = s; i < (int)n; i++)
#define per(i, n) for(int i = n; i >= 0; i--)
#define ROF(i, s, n) for(int i = s; i >= (int)n; i--)
#define FORIT(i, A) for (auto i : A)
#define PRINT(x) cout << (x) << "\n"
#define ALL(a) (a).begin(),(a).end()
#define RALL(a) (a).rbegin(), (a).rend()
#define MP make_pair
#define EACH(i, n) for (__typeof((n).begin()) i = (n).begin(); i != (n).end(); ++i)
#define SZ(a) int((a).size())
#define EXIST(s,e) ((s).find(e)!=(s).end())
#define SORT(c) sort((c).begin(),(c).end())
#define CLR(a) memset((a), 0 ,sizeof(a))
#define NCLR(a) memset((a), -1 ,sizeof(a))
#define dump(x) cout << #x << " = " << (x) << "\n";
#define debug(x) cout << #x << " = " << (x) << " (L" << __LINE__ << ")" << " " << __FILE__ << "\n";
#define sq(n) (n) * (n)
typedef vector<int> VI;
typedef vector<VI> VVI;
typedef vector<string> VS;
typedef pair<int, int> PII;
typedef long long LL;
typedef vector<LL> VLL;
typedef vector<VLL> VVLL;
typedef unsigned int uint;
typedef unsigned long long ull;
typedef priority_queue<int> maxpq;
typedef priority_queue< int, vector<int>, greater<int> > minpq;
typedef complex<double> P;
static const double EPS = 1e-10;
static const double PI = acos( -1.0 );
static const int mod = 1000000007;
static const int INF = 1 << 29;
static const LL LL_INF = 1152921504606846976;
static const int dx[] = { -1, 0, 1, 0, 1, -1, 1, -1 };
static const int dy[] = { 0, -1, 0, 1, 1, 1, -1, -1 };


int main() {
	int n, m;
	bool cpu[ 20000 ];
	vector<pair<int, PII> > d;
	while ( ~scanf( "%d %d", &n, &m ) && n ) {
		cpu[ 0 ] = true;
		CLR( cpu );
		cpu[ 0 ] = true;
		d.clear();
		for ( int i = 0; i < m; i++ ) {
			int time, from, to;
			scanf( "%d %d %d", &time, &from, &to );
			d.push_back( MP( time, MP( from - 1, to - 1 ) ) );
		}
		sort( d.begin(), d.end() );
		for ( int i = 0; i < m; i++ ) {
			if ( cpu[ d[ i ].second.first ] ) {
				cpu[ d[ i ].second.second ] = true;
			}
		}
		int ans = 0;
		for ( int i = 0; i < n; i++ ) {
			ans += cpu[ i ];
		}
		printf( "%d\n", ans );
	}
	return 0;
}