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>
#define ll long long
#define INF 1000000005
#define MOD 1000000007
#define EPS 1e-10
#define rep(i,n) for(int i=0;i<(int)(n);++i)
#define rrep(i,n) for(int i=(int)(n)-1;i>=0;--i)
#define srep(i,s,t) for(int i=(int)(s);i<(int)(t);++i)
#define each(a,b) for(auto (a): (b))
#define all(v) (v).begin(),(v).end()
#define len(v) (int)(v).size()
#define zip(v) sort(all(v)),v.erase(unique(all(v)),v.end())
#define cmx(x,y) x=max(x,y)
#define cmn(x,y) x=min(x,y)
#define fi first
#define se second
#define pb push_back
#define show(x) cout<<#x<<" = "<<(x)<<endl
#define spair(p) cout<<#p<<": "<<p.fi<<" "<<p.se<<endl
#define svec(v) cout<<#v<<":";rep(kbrni,v.size())cout<<" "<<v[kbrni];cout<<endl
#define sset(s) cout<<#s<<":";each(kbrni,s)cout<<" "<<kbrni;cout<<endl
#define smap(m) cout<<#m<<":";each(kbrni,m)cout<<" {"<<kbrni.first<<":"<<kbrni.second<<"}";cout<<endl

using namespace std;

typedef pair<int,int> P;
typedef vector<int> vi;
typedef vector<vi> vvi;
typedef vector<ll> vl;
typedef vector<double> vd;
typedef vector<P> vp;

const int MAX_N = 100005;

struct tri
{
    int t,s,d;
    bool operator<(const tri& another) const {
        return t < another.t;
    }
};

class UF {
private:
    int sz; vector<int> par,nrank,size;
public:
    UF(){}
    UF(int node_size){ sz = node_size; par.resize(sz),nrank.resize(sz),size.resize(sz);
        rep(i,sz){ par[i] = i; nrank[i] = 0; size[i] = 1;} }
    int find(int x){ if(par[x] == x){ return x; }else{ return par[x] = find(par[x]); } }
    void unite(int x,int y)
    { x = find(x),y = find(y); if(x == y) return; if(nrank[x] < nrank[y]) swap(x,y);
        par[y] = x; size[x] += size[y]; if(nrank[x] == nrank[y]) nrank[x]++; }
    int query(int x){ x = find(x); return size[x]; }
    bool same(int x,int y){ return find(x) == find(y); }
};

int main()
{
    cin.tie(0);
    ios::sync_with_stdio(false);
    while(1){
        int n,m;
        cin >> n >> m;
        if(n == 0){
            break;
        }
        vector<tri> vec(m);
        rep(i,m){
            int t,s,d;
            cin >> t >> s >> d;
            s--,d--;
            vec[i] = (tri){t,s,d};
        }
        sort(all(vec));
        UF uf(n);
        rep(i,m){
            if(uf.same(0,vec[i].s)){
                uf.unite(0,vec[i].t);
            }
        }
        cout << uf.query(0) << endl;
    }
    return 0;
}

C++: #include<iostream>
#define loop(i,a,b) for(int i=a;i<b;i++)
#define rep(i,a) loop(i,0,a)
using namespace std;

int main(){
	int n,m;
	while(cin>>n>>m,n||m){
		bool infect[n+1];
		rep(i,n+1)infect[i]=false;
		infect[1]=true;
		long long ans=1;
		long long t[m];
		int s[m],d[m];
		rep(i,m)cin>>t[i]>>s[i]>>d[i];
		for(int i=m;i>=0;i--){
			for(int j=0;j<i-1;j++){
				if(t[j]>t[j+1]){
					long long alt=t[j];
					t[j]=t[j+1];
					t[j+1]=alt;
					alt=s[j];
					s[j]=s[j+1];
					s[j+1]=alt;
					alt=d[j];
					d[j]=d[j+1];
					d[j+1]=alt;
				}
			}
		}
		rep(i,n){
			if(infect[s[i]]){
				if(!infect[d[i]])ans++;
				infect[d[i]]=true;
			}
		}
		cout<<ans<<endl;
	}
	return 0;
}

C++: #include<iostream>
#include<algorithm>
using namespace std;
typedef pair<int, pair<int, int>> p;
int main() {
    int n, m;
    while (cin >> n >> m, n, m) {
        bool b[20010] = {};
        b[1] = true;
        p a[20010];
        for (int i = 0; i < m; i++)cin >> a[i].first >> a[i].second.first >> a[i].second.second;
        sort(a, a + m);
        for (int i = 0; i < m; i++) 
            if (b[a[i].second.first])b[a[i].second.second] = true;
        int ans = 0;
        for (int i = 1; i <= n; i++)if (b[i])ans++;
        cout << ans << endl;
    }
}