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 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;
	while ( ~scanf( "%d %d", &n, &m ) && n && m ) {
		VI cpu( n, false );
		cpu[ 0 ] = true;
		vector<pair<int, PII> > d;
		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 ) ) );
		}
		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++ ) {
			if ( cpu[ i ] ) {
				++ans;
			}
		}
		printf( "%d\n", ans );
	}
	return 0;
}

C++: #include <iostream>
#include <algorithm>
#include <cstdio>
#include <string>
#include <cstring>
#include <cctype>
#include <cstdlib>
#include <cmath>
#include <vector>
#include <set>
#include <queue>
#include <stack>
#include <map>
using namespace std;

#define REP(i, s, e) for (int i = (s); i < (e); i++)
#define REPI(i, s, e) for (int i = (s); i <= (e); i++)
#define rep(i, n) REP(i, 0, n)
#define repi(i, n) REPI(i, 0, n)
#define ALL(v) (v).begin(), (v).end()

#define dump(x) (cout << #x << " = " << x << endl)
#define dump2(x, y) (cout << "(" << #x << ", " << #y << ") = (" << x << ", " << y << ")" << endl)
#define dump3(x, y, z) (cout << "(" << #x << ", " << #y << ", " << #z << ") = (" << x << ", " << y << ", "<< z << ")" << endl)

typedef long long ll;
typedef pair<int, int> pii;

int N, M;

class node{
public:
	int t, s, d;
	node(int t, int s, int d):t(t), s(s), d(d){}

	bool operator<(const node& r) const {
		return t < r.t;
	}
};

#define MAX 20002
int prev[MAX];
bool has_parent[MAX];

int main(void)
{
	while (cin >> N >> M, N|M) {
		vector<node> ns;

		rep(i, M) {
			int t, s, d;
			cin >> t >> s >> d;
			ns.push_back(node(t, --s, --d));
		}
		sort(ALL(ns));

		memset(prev, -1, sizeof(prev));
		fill(has_parent, has_parent+MAX, false);
		rep(i, ns.size()) {
			node n = ns[i];
			prev[n.d] = n.s;
		}

		rep(i, N)
			if (prev[i] != -1)
				has_parent[prev[i]] = true;
		rep(i, N)
			if (prev[i] != -1 && !has_parent[i])
				cout << i+1 << endl;
	}
	return 0;
}

C++: #include <cstdio>
#include <cstdlib>
#include <utility>
#include <typeinfo>
#include <cmath>
#include <numeric>
#include <algorithm>
#include <iostream>
#include <sstream>
#include <iomanip>
#include <vector>
#include <string>
#define REP(i,n) for(int i=0;i<n;i++)
typedef long long ll;
using namespace std;
typedef vector<ll> vl;
typedef pair<ll,ll> pll;
typedef vector<pll> vpll;
typedef vector<string> vs;

int main() 
{
	int n,m;
	while(cin>>n>>m&&!(n==0&&m==0))
	{
		pair<int,int> a[20000],b[20000];
		REP(i,m)
		{
			int x,y,z;
			scanf("%d%d%d",&x,&y,&z);
			y-=1;z-=1;
			a[i] = make_pair(x,y);
			b[i] = make_pair(x,z);
		}
		sort(a,a+m);
		sort(b,b+m);
		
		bool inf[20000]={};
		inf[0]=true;
		
		int ans(1);
		REP(i,m){if(inf[a[i].second]&&!inf[b[i].second]){inf[b[i].second]=true;++ans;}}

		printf("%d",ans);
	}
	return 0;
}