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<queue>
using namespace std;
int main(){
  while(1){
    int n;
    string a[10001],b;
    queue<string> c;
    cin>>n;
    if(n==0)break;
    for(int i=0;i<n;i++){
      cin>>a[i]>>b;
      c.push(b);
    }
    int cnt=0;
    for(int i=0;i<n;i++){
      if(a[i]>=c.front()){
	c.pop();
      }else cnt++;
    }
    cout<<cnt<<endl;
  }
  return 0;
}

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

int main(void){
	int i,j,n,th,tm,ts,s[10000],g[10000],flg[10000];
	int max,sum;
	char c;

	while(cin>>n && n){
		max = sum = 0;

		for(i=0;i<n;i++){
			cin>>th>>c>>tm>>c>>ts;
			s[i] = ts + tm * 60 + th * 3600;
			cin>>th>>c>>tm>>c>>ts;
			g[i] = ts + tm * 60 + th * 3600;
		}

		for(i=0;i<n-1;i++){
			for(j=i+1;j<n;j++){
				if(s[i] > s[j] || s[i] == s[j] && g[i] > g[j]){
					swap(s[i],s[j]);
					swap(g[i],g[j]);
				}
			}
		}

		for(i=0;i<n;i++){
			for(j=0;j<i;j++){
				if(s[i] >= g[j] && flg[j]){
					sum--;
					flg[j] = 0;
				}
			}
			sum++;
			flg[i] = 1;
			if(max < sum) max = sum;
		}
		cout<<max<<endl;
	}

	return 0;
}

C++: #include <iostream>
#include <string>
#include <algorithm>

using namespace std;
int N;
string In[10000], Out[10000];
int main() {
  while (cin >> N && N > 0) {
    for (int i=0; i<N; ++i)
      cin >> Out[i] >> In[i];
    sort(In, In+N);
    sort(Out, Out+N);
    //    for (int i=0; i<N; ++i)
    //      cout << Out[i] << ' ' << In[i] << endl;
  }

  int p=0, taiki=0, train=0;
  for (int i=0; i<N; ++i) {
    while (p<N && In[p] <=Out[i]) {
      taiki++;
      p = p+1;
    }
    if (taiki > 0) taiki = taiki - 1;
    else train = train + 1;
  }
  cout << train << endl;
}

C++: #include<iostream>
#include<string>
#include<vector>
#include<map>
#include<algorithm>
using namespace std;
typedef pair<int,int> se;
typedef vector<se> tt;
int main(){
  int n;
  cin>> n;
  while(n!=0){
    int i,j,k;
    string str;
    tt t;
    for(i=0;i<n;i++){
      int st=0,et=0;
      cin >> str;
      st+=((str[0]-'0')*10+str[1]-'0')*24*60;
      st+=((str[3]-'0')*10+str[4]-'0')*60;
      st+=((str[6]-'0')*10+str[7]-'0');
      cin >> str;
      et+=((str[0]-'0')*10+str[1]-'0')*24*60;
      et+=((str[3]-'0')*10+str[4]-'0')*60;
      et+=((str[6]-'0')*10+str[7]-'0');
      t.push_back(make_pair(st,et));
    }
    sort(t.begin(),t.end());
    int m=0,b;
    for(j=0;j<86401;j++) {
      b=0;
      for(k=0;k<t.size();k++){
	if(t[k].first<=j&&j<t[k].second) b++;
      }
      if(m<b) m=b;
    }
    cout << m << endl;
    cin >> n;
  }
  return 0;
}

C++: //35
#include<iostream>
#include<algorithm>
#include<string>
#include<utility>

using namespace std;

int main(){
  for(int n;cin>>n,n;){
    pair<string,int> t[20000];
    for(int i=0;i<n;i++){
      string s,g;
      cin>>s>>g;
      t[2*i]=make_pair(s,1);
      t[2*i+1]=make_pair(g,-1);
    }
    sort(t,t+2*n);
    int m=0,c=0;
    for(int i=0;i<n*2;i++){
      c+=t[i].second;
      m=max(m,c);
    }
    cout<<m<<endl;
  }
  return 0;
}

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



int main(){
  while(1){


    
  int n;
  cin>>n;
  if(n==0){break;}
  int t[1000000]={};
  for(int i=0;i<n;i++){
    int h,m,s;
    char c;
    cin>>h>>c>>m>>c>>s;
    int a=h*60*60+m*60+s;
    t[a]++;
    cin>>h>>c>>m>>c>>s;
    a=h*60*60+m*60+s;
    t[a]--;
  }
  int mx=0;
  int count=0;
  for(int i=0;i<1e6;i++){
    count+=t[i];
    mx=max(mx,count);
  }
  cout<<mx<<endl;
  



  }
  return 0;
}