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 = 0;

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

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

int main(){
    int n;

    cin >> n;

    vector<int> retime(360000);
    int ans=0;
    for (int i = 0; i < n;i++)
    {
        int h, m, s;
        int entime;
        int detime;

        scanf("%d:%d:%d", &h, &m, &s);
        retime[h * 60 * 60 + m * 60 + s]++;
        scanf("%d:%d:%d", &h, &m, &s);
        retime[h * 60 * 60 + m * 60 + s]--;
    }

    for (int i = 1; i < 360000;i++){
        retime[i] += retime[i - 1];
    }

    ans = *max_element(retime.begin(), retime.end());

    cout << ans << endl;
}

C++: #include <iostream>
#include <cstdio>
#include <utility>
#include <vector>
#include <algorithm>
#define REP(i,n) for(int i=0;i<(n);i++)
using namespace std;

typedef pair<int,int> pii;

int main()
{
  while(1){
    int n;
    scanf("%d", &n);
    if(n == 0) break;
    vector<pii> time(n);
    REP(i,n){
      int h, m, s;
      scanf("%d:%d:%d", &h, &m, &s);
      time[i].first = h*3600 + m*60 + s;
      scanf("%d:%d:%d", &h, &m, &s);
      time[i].second = h*3600 + m*60 + s;
    }
    sort(time.begin(),time.end());
    int ans = 1;
    int t = 1;
    vector<int> f;
    REP(i,n){
      if(!f.empty())
        REP(j,(int)f.size())
          if(f[j] <= time[i].first){
            t++;
            f.erase(f.begin()+j);
          }
      if(t > 0){
        t--;
        f.push_back(time[i].second);
      }else{
        ans++;
        f.push_back(time[i].second);
      }
    }
    cout << ans << endl;
  }
}

C++: 
#include <iostream>
#include <stdio.h>
#include <string>
#include <sstream>
#include <vector>
#include <stdlib.h>
#include <math.h>

#define timemax 24*60*60 + 1
using namespace std;

int main(void){
	//FILE* fp_in = freopen("data.txt", "r", stdin);
	
	//imos法を用いる
	
	while(1) {
		int n;
		scanf("%d",&n);
		if( n == 0 ) break;
		vector<int> time;
		
		for(int i = 0; i < timemax; i++)
			time.push_back(0);

		for(int i = 0; i < n; i++) {
			for(int j = 0; j < 2; j++){
				int h,m,s;
				scanf("%02d:%02d:%02d", &h, &m, &s);
				if(j == 0) time.at(h*3600 + m*60 + s) ++;
				else time.at(h*3600 + m*60 + s) --;
			}
		}

		//最大値を求める
		int max = 0;
		for(int i = 1; i < time.size(); i++)
			time.at(i) += time.at( i - 1 );

		for(int i = 0; i < time.size(); i++)
			if( time.at(i) > max ) max = time.at(i);

		cout << max << endl;

	}

	
	//while(1){}
	return 0;
}

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

int main() {
	int n;
	while(cin >> n && n){
		int hs, ms, ss, he, me, se, count[24 * 3600] = {0};
		for(int i = 0; i < n; ++i){
			char c;
			scanf("%d:%d:%d", &hs, &ms, &ss);
			scanf("%d:%d:%d", &he, &me, &se);
			/*scanf("%d%c%d%c%d", hs, c, ms, c, ss);
			scanf("%d%c%d%c%d", he, c, me, c, se);*/
			for(int j = hs * 3600 + ms * 60 + ss; j < he * 3600 + me * 60 + se; ++j){
				count[j]++;
			}
		}
		int ans = 0;
		for(int i = 0; i < 24 * 3600; ++i){
			ans = max(ans, count[i]);
		}
		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()]--;
        }
        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;
    }
}