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 <bits/stdc++.h>
#define rep(i, n) for (int i = 0; i < (n); i++)
#define shosu(n) setprecision(n)
#define INF 999999999
using namespace std;
int main() {
  int n, t[86400 + 1];
  while (cin >> n, n) {
    memset(t, 0, sizeof(t));
    int H1, H2, M1, M2, S1, S2;
    for (int i = 0; i < n; i++) {
      scanf("%d:%d:%d %d:%d:%d", &H1, &M1, &S1, &H2, &M2, &S2);
      t[H1 * 3600 + M1 * 60 + S1]++;
      t[H2 * 3600 + M2 * 60 + S2]--;
    }
    int ans = 0;
    for (int i = 1; i <= 86400; i++)
      t[i] += t[i - 1];
    cout << *max_element(t, t + 86400) << endl;
  }
  return 0;
}

C++: #include<iostream>
#include<cstdio>
#include<string>
#include<vector>
#include<map>
#include<algorithm>
using namespace std;
#define P pair<int,int>//出発、到着

vector<P>ta;
bool used[11000];
void init(string x,string y){
			int s,e;
	string a=x.substr(0,2),b=x.substr(3,2),c=x.substr(6,2);
	int aa=(a[0]-'0')*10+(a[1]-'0');
	int bb=(b[0]-'0')*10+(b[1]-'0');
	int cc=(c[0]-'0')*10+(c[1]-'0');
	s=aa*3600+bb*60+cc;
	 a=y.substr(0,2),b=y.substr(3,2),c=y.substr(6,2);
	 aa=(a[0]-'0')*10+(a[1]-'0');
	 bb=(b[0]-'0')*10+(b[1]-'0');
	cc=(c[0]-'0')*10+(c[1]-'0');
	e=aa*3600+bb*60+cc;
	P tmp=make_pair(s,e);
	ta.push_back(tmp);

}
bool ok(int n){
for(int i=0;i<n;i++)if(used[i]==0)return false;
return true;
}
int main(){
	int n;
	while(true){
	cin>>n;
	if(n==0)break;
	ta.clear();
for(int i=0;i<n;i++){
	string x,y;
	cin>>x>>y;
	init(x,y);
}
int ans=1;
fill(used,used+11000,false);
	//trueなら使ったってこと
	
	int now=0,j=0,b=9999999,next=0;
	while(ok(n)==false){
	//for(int i=0;i<n;i++)cout<<used[i]<<" ";cout<<endl;
	for(int i=0;i<n;i++){
	if(ta[i].first>=now&&used[i]==0&&b>ta[i].first){
	b=ta[i].second;
	j=i;
	}
	}
	
	next=ta[j].second;
	if(now!=next){
	now=next;
	used[j]=1;
	b=9999999;
	}
	else {
	ans++;
	now=0,next=0;
	b=9999999;
	}
}
	cout<<ans<<endl;
}
	return 0;
}

C++: #include<stdio.h>
#include<iostream>
using namespace std;

int main(){

int n,q;
int h1=0,m1=0,s1=0,h2=0,m2=0,s2=0;
while(1){
cin>>n;if(n==0)break;
long long int N[90800]={};
for(int i=0;i<n;i++)
{scanf("%d:%d:%d",&h1,&m1,&s1);
scanf("%d:%d:%d",&h2,&m2,&s2);
long int L1=h1*3600+m1*60+s1;
long int L2=h2*3600+m2*60+s2;
for(int j=L1;j<L2;j++)
	N[j]++;
}
int max=0;
for(int i=0;i<90800;i++)
{if(N[i]>max)max=N[i];}
cout<<max<<endl;
}
return 0;
}

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

typedef pair<int,int> pii;

vector<pii>train;
const int H=60*60;
const int M=60;
const int S=1;
int unit[3]={H,M,S};

int getTime(string s){
  string tmp;
  int res=0;
  for(int i=0;i<3;i++){
    tmp=s.substr(3*i,2);
    int val=unit[i]*atoi(tmp.c_str());
    res+=val;
  }
  return res;
}

void makeEvent(string start,string arrival){
  int st=getTime(start);
  int at=getTime(arrival);
  train.push_back(make_pair(st,1));
  train.push_back(make_pair(at,0));
}

int main(){
  int n;
  while(cin>>n,n){
    train.clear();
    for(int i=0;i<n;i++){
    string start,arrival;
    cin>>start>>arrival;
    makeEvent(start,arrival);
    }
    int ans=0,tmp=0;
    sort(train.begin(), train.end());
    for(pii i:train){
      if(i.second==1){
	tmp++;
      }else{
	tmp--;
      }
      ans=max(tmp,ans);
    }
    cout << ans << endl;
  }
  return 0;
}