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 <string>
#include <algorithm>
#include <functional>
#include <vector>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <cmath>
using namespace std;
typedef long long ll;
typedef pair<int,int> pint;
typedef vector<int> vint;
typedef vector<pint> vpint;
#define mp make_pair
#define fi first
#define se second
#define all(v) (v).begin(),(v).end()
#define rep(i,n) for(int i=0;i<(n);i++)
#define reps(i,f,n) for(int i=(f);i<(n);i++)

void slove(int n){
	vector<int> v(86400);
	rep(i, 86400) v[i] = 0;//?????????
	rep(i, n){
		string s, e;
		cin >> s >> e;
		//?§???°?????????
		int start = 36000 * (s[0] - '0') + 3600 * (s[1] - '0') 
					+ 600 * (s[3] - '0') + 60 * (s[4] - '0')
					+ 10 * (s[6] - '0') + 1 * (s[7] - '0');
		int end = 36000 * (e[0] - '0') + 3600 * (e[1] - '0') 
					+ 600 * (e[3] - '0') + 60 * (e[4] - '0')
					+ 10 * (e[6] - '0') + 1 * (e[7] - '0');
		printf("%d %d\n", start, end);
		for (int j = start; j < end ; ++j) v[j]++;//???????????????
	}
	int ans;

	rep(i, 86400){
		ans = max(ans, v[i]);
	}
	//sort(all(v));
	//reverse(all(v));
	printf("%d\n", ans);
	return;
}
int main(void){
	rep(i, 100000000){
		int n; scanf("%d", &n);
		if(n == 0) break;
		slove(n);
	}
	return 0;
}

C++: #include<iostream>
#include<algorithm>
using namespace std;

#define DAY_TIME 86400

//??¢??°(00:00:00??????????§???°?????????)
int timeToNum(char* text) {
	int ans=0;
	//h
	ans += (text[0] - '0') * 60 * 60 * 10;
	ans += (text[1] - '0') * 60 * 60;
	//m
	ans += (text[3] - '0') * 60 * 10;
	ans += (text[4] - '0') * 60;
	//s
	ans += (text[6] - '0') * 10;
	ans += (text[7] - '0');

	return ans;
}

//?????????????????????
int imosu[DAY_TIME];

//??????????????¨??????
int N;

//??????????????¨??°?????????
char timeS[100];
char timeE[100];

//??????
int ans;

int main() {
	while (true) {
		//?????????
		for(int i=0;i<DAY_TIME;i++)imosu[i]=0;
		ans=0;

		//??\?????¨???????????¶
		cin>>N;
		if(N==0)break;

		for(int i=0;i<N;i++){
			//??\???
			cin >> timeS;
			cin >> timeE;
			
			//???????????????????????????
			imosu[timeToNum(timeS)]++;
			imosu[timeToNum(timeE)]--;
		}

		//????????????????????????????????????
		for (int i = 0; i < DAY_TIME-1; i++) {
			imosu[i+1]+=imosu[i];
			ans=max(ans,imosu[i+1]);
		}
		//?????§????????????
		cout<<ans<<endl;
	}
	return 0;
}

C++: #include<iostream>
#include<cstdio>
#include<queue>
using namespace std;
#define MAX 10000
struct Train{
	int st;
	int ed;
	void SetSt(int h, int m, int s){
		st = h * 3600 + m * 60 + s;
	}
	void SetEd(int h, int m, int s){
		ed = h * 3600 + m * 60 + s;
	}
	bool operator<(const Train &t)const{
		return ed < t.ed;
	}
};
int main(){
	while(true){
		unsigned int ans = 0;
		int n;
		priority_queue< Train > pq;
		scanf("%d", &n);

		if( n == 0 ) break;

		for(int i = 0; i < n; ++i){
			int sh,sm,ss;
			int eh,em,es;
			Train t;
			
			scanf("%02d:%02d:%02d %02d:%02d:%02d",
				&sh,&sm,&ss,
				&eh,&em,&es);
			t.SetSt( sh, sm, ss );
			t.SetEd( eh, em, es );
			
			if( pq.size() == 0 )
				pq.push( t );
			else{
				Train tt = pq.top();
				if( !(tt < t) )
					pq.push( t );
				else
					pq.pop();
			}
			ans = max(ans, pq.size());
		}
		printf("%d\n", ans);
	}
	return 0;
}

C++: #include<iostream>
#include<algorithm>
#include<cstdio>
using namespace std;
int ta[24*60*60];
int main(){
	int n;
	while(true){
	cin>>n;
	if(n==0)break;
	for(int i=0;i<24*60*60;i++)ta[i]=0;
	int a,b,c,d,e,f;
	for(int i=0;i<n;i++){
	scanf("%d:%d:%d %d:%d:%d",&a,&b,&c,&d,&e,&f);
	int now=a*3600+b*60+c,next=d*3600+e*60+f;
	ta[now]++;
	ta[next]--;
	}
	for(int i=0;i<24*60*60-1;i++)ta[i+1]+=ta[i];
	int ans=0;
	for(int i=0;i<24*60*60;i++)ans=max(ans,ta[i]);
	cout<<ans<<endl;
	}
	return 0;
}

C++: #include<iostream>
#include<cstdio>
using namespace std;

int main(){
  int n;
  while(cin>>n,n){
    int data[86401]={0};
    for(int i=0;i<n;i++){
      int hh1,mm1,ss1;
      int hh2,mm2,ss2;
      int time1,time2;
      scanf("%d:%d:%d %d:%d:%d",&hh1,&mm1,&ss1,&hh2,&mm2,&ss2);
      time1=hh1*3600+mm1*60+ss1;
      time2=hh2*3600+mm2*60+ss2;
      for(int i=time1;i<time2;i++){
	data[i]++;
      }
    }
    int max=0;
    for(int i=0;i<86401;i++){
      max =((max < data[i])?(data[i]):(max));
    }
    cout<<max<<endl;
  }
  return 0;
}

C++: #include <algorithm>
#include <iostream>
#include <cstdio>
#include <vector>
#include <utility>
using namespace std;

int main(){
  auto read = [](){
                int hh,mm,ss;
                scanf("%d:%d:%d",&hh,&mm,&ss);
                return hh*3600 + mm*60 + ss;
              };

  int n;
  while(cin >> n, n){

    vector<pair<int,int>> T;
    for(int i = 0; i < n; ++i){
      int in = read(), out = read();
      T.emplace_back(in,1);
      T.emplace_back(out,-1);
    }
    sort(T.begin(), T.end());
    int cnt = 0, t = 0;
    for(auto e : T){
      t -= e.second;
      if(t < 0) ++cnt, ++t;
    }
    cout << cnt << endl;
  }
}