Go: package main

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

func main() {
	io := NewIo()
	defer io.Flush()
	for {
		n := io.NextInt()
		if n == 0 {
			break
		}
		accum := make([]int, 86401)
		for i := 0; i < n; i++ {
			s, e := io.Next(), io.Next()
			hs, _ := strconv.Atoi(s[:2])
			ms, _ := strconv.Atoi(s[3:5])
			ss, _ := strconv.Atoi(s[6:8])
			accum[hs*60*60+ms*60+ss]++
			he, _ := strconv.Atoi(e[:2])
			me, _ := strconv.Atoi(e[3:5])
			se, _ := strconv.Atoi(e[6:8])
			accum[he*60*60+me*60+se]--
		}
		ans := 0
		for i := 1; i < 86401; i++ {
			accum[i] += accum[i-1]
			ans = intMax(accum[i], ans)
		}
		io.Println(ans)
	}
}

func intMax(a, b int) int {
	if a < b {
		return b
	}
	return a
}

// 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 := []interface{}{}
	for _, x := range a {
		b = append(b, x)
	}
	io.Println(b...)
}

func (io *Io) PrintStringSlice(a []string) {
	b := []interface{}{}
	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 <iostream>
#include <cstdio>
#include <vector>
#include <map>
#include <algorithm>
using namespace std;

int main(void){
  int n;
  while(cin>>n,n){
    vector<pair<int,int> > timetable(n);
    for(int i=0;i<n;++i){
      int sh,sm,ss,eh,em,es;
      scanf("%d:%d:%d",&sh,&sm,&ss);
      scanf("%d:%d:%d",&eh,&em,&es);
      timetable[i]=make_pair(sh*3600+sm*60+ss,eh*3600+em*60+es);
    }
    int ans=0;
    for(int i=0,sti,eti;i<n;++i){
    	int cnt=1;
      sti=timetable[i].first;
      eti=timetable[i].second;
      for(int j=0,stj,etj;j<n;++j){
        if(i==j)continue;
        stj=timetable[j].first;
        etj=timetable[j].second;
        if((sti<=stj&&stj<eti)||(sti<etj&&etj<=eti)||(stj<=sti&&eti<=etj))++cnt;
      }
      ans=max(ans,cnt);
    }
    cout<<ans<<endl;
  }
  return 0;
}

C++: #include<iostream>
#include<vector>
#include<string>
#include<algorithm>
using namespace std;
int in(){
    string s;
    cin >> s;
    for(int i = 0; i < s.size(); i++)s[i] -= '0';
    int h = s[0]*10 + s[1];
    int m = s[3]*10 + s[4];
    int ret = s[6]*10 + s[7];
    ret += m * 60 + h * 60*60;
    return ret;
}
int main(){
    int n;
    while(cin >> n, n){
        vector<int> imos(24*60*60+5);
        while(n--){
            imos[in()]++;
            imos[in()+1]--;
        }
        for(int i = 1; i < 24*60*60+5; i++)imos[i] += imos[i-1];
        int ans = 0;
        for(int i = 0; i < 24*60*60+5; i++)ans = max(ans, imos[i]);
        cout << ans << endl;
    }
}

C++: #include <bits/stdc++.h>
#define INF 1000000000
using namespace std;

int change_to_sec(string time)
{
  int hour = stoi(time.substr(0, 2));
  int minute = stoi(time.substr(3, 2));
  int sec = stoi(time.substr(6, 2));
  // cout << hour << ' ' << minute << ' ' << sec << endl;
  sec += hour * 3600 + minute * 60;
  // cout << sec << endl;
  return sec;
}

int main()
{
  while (true)
  {
    int n;
    cin >> n;
    if (n == 0)
    {
      break;
    }
    vector<int> time_table(86401, 0);
    for (int i = 0; i < n; ++i)
    {
      string start, end;
      cin >> start;
      cin >> end;
      int sec = change_to_sec(start);
      time_table.at(sec) += 1;
      sec = change_to_sec(end);
      time_table.at(sec) -= 1;
    }
    int ans = time_table.at(0);
    // for (int i = 0; i < 86400; ++i)
    // {
    //   if (time_table.at(i) != 0)
    //   {
    //
    //     cout << time_table.at(i) << endl;
    //   }
    // }
    for (int i = 0; i < 86400; ++i)
    {
      time_table.at(i + 1) += time_table.at(i);
      ans = max(ans, time_table.at(i + 1));
    }
    cout << ans << endl;
  }
}

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

int main() {
	while(1){
		int n;
		cin >> n;
		if(n==0) break;
		vector<int> s(n),g(n);
		vector<int> m(86400);
		for(int i=0; i<n; i++){
			string a,b;
			cin >> a >> b;
			s.at(i)=stoi(a.substr(0,2))*3600+stoi(a.substr(3,2))*60+stoi(a.substr(6,2));
			g.at(i)=stoi(b.substr(0,2))*3600+stoi(b.substr(3,2))*60+stoi(b.substr(6,2));
			m.at(s.at(i))++;
			m.at(g.at(i))--;
		}
		int ans{}, cnt{};
		for(int i=0; i<86400; i++){
			cnt += m.at(i);
			ans = max (ans, cnt);
		}
		cout << ans << endl;
	}
	
}

C++: #include<iostream>
#include<iomanip>
#include<algorithm>
#include<bitset>
#include<cctype>
#include<cmath>
#include<cstdio>
#include<cstring>
#include<functional>
#include<limits>
#include<list>
#include<map>
#include<set>
#include<stack>
#include<string>
#include<sstream>
#include<queue>
#include<vector>
using namespace std;
 
#define MOD 1000000007
#define INF 0x3f3f3f3f
#define INFL 0x3f3f3f3f3f3f3f3fLL
 
int main() {
    int s[10000], g[10000], f[10000]={}, hhs, mms, sss, hhg, mmg, ssg, cnt = 1,n;
    while(1){
        cin>>n;
        if(n==0)break;
        for (int i = 0; i < n; i++) {
            char c;
            cin >> hhs >> c >> mms >> c >> sss >> hhg >> c >> mmg >> c >> ssg;
 
            s[i] = 3600 * hhs + 60 * mms + sss;
            g[i] = 3600 * hhg + 60 * mmg + ssg;
        }
		
		for(int i=0;i<n-1;i++)
			for(int j=n-1;j>i;j--)
				if(s[j-1]>s[j]){
					int tmp=s[j];
					s[j]=s[j-1];
					s[j-1]=tmp;
					tmp=g[j];
					g[j]=g[j-1];
					g[j-1]=tmp;
				}
		
		
		
        for (int i = 1; i < n; i++) {
            for (int j = 0; j < i;) {
                //cout << "j" << endl;
                if (f[j] == 1) { j++; continue; }
                if (s[i] >= g[j]) {
                    f[j] = 1;
                    break;
                }
                j++;
                if (j == i)cnt++;
            }
            //cout << "i" << endl;
        }
        //cout << "h" << endl;
        cout << cnt << endl;
        cnt = 1;
 
    }
    return 0;
}