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 <vector>
#include <iostream>
#include <utility>
#include <algorithm>
#include <string>
#include <deque>
#include <queue>
#include <tuple>
#include <queue>
#include <functional>
#include <cmath>
#include <iomanip>
#include <map>
#include <set>
#include <numeric>
#include <unordered_map>
#include <unordered_set>
#include <complex>
#include <iterator>
#include <array>
#include <memory>
#include <stack>
#define vi vector<int>
#define vvi vector<vector<int> >
#define ll long long int
#define vl vector<ll>
#define vvl vector<vector<ll>>
#define vb vector<bool>
#define vc vector<char>
#define vs vector<string>
#define ld long double
#define INF 1e9
#define EPS 0.0000000001
#define rep(i,n) for(int i=0;i<n;i++)
#define loop(i,s,n) for(int i=s;i<n;i++)
#define all(in) in.begin(), in.end()
template<class T, class S> void cmin(T &a, const S &b) { if (a > b)a = b; }
template<class T, class S> void cmax(T &a, const S &b) { if (a < b)a = b; }
#define MAX 9999999
using namespace std;
typedef pair<int, int> pii;
typedef pair<double,double>pdd;
typedef pair<ll,ll>pll;
typedef pair<int,pii>ppii;
typedef pair<ppii,ppii> d_pii;
ppii cal(string s){
    ppii temp;
    string a,b,c;
    a=s[0]; a+=s[1];
    b=s[3];b+=s[4];
    c=s[6];c+=s[7];
    temp.first=stoi(a);
    temp.second=pii(stoi(b),stoi(c));
    return temp;
}
int main(){
    int n;
    while(cin>>n,n){
        vector<pair<ll,ll>>v;
        rep(i,n){
            string s,e; cin>>s>>e;
            ppii start,end;
            start=cal(s);
            end=cal(e);
            ll _start=start.first*3600+start.second.first*60+start.second.second;
            ll _end=end.first*3600+end.second.first*60+end.second.second;
            //cout<<start.first<<":"<<start.second.first<<":"<<start.second.second<<endl;
            //cout<<end.first<<":"<<end.second.first<<":"<<end.second.second<<endl;
            v.push_back(make_pair(_start,_end));
        }
        sort(all(v));
        vl u(v.size());
        rep(i,v.size())u[i]=v[i].first;
        ll ans=0;
        ll base=0;
        u.push_back(INF);
        v.push_back(pii(INF,INF));
        rep(i,u.size()){
            ans++;
            base=v[i].second;
            while(true){
                bool update=false;
                vector<ll>::iterator itr=lower_bound(u.begin(), u.end(),base);
                if(itr!=u.end()){
                    int index=(int)(itr-u.begin());
                    update=true;
                    //cout<<*itr<<endl;
                    u.erase(itr);
                    base=v[index].second;
                    v.erase(v.begin()+index);
                }
                if(!update)break;
            }
        }
        cout<<ans<<endl;
    }
}

C++: #include <iostream>
#include <string>
#include <algorithm>
#include <vector>
using namespace std;
static const int N = 10000;
int Change(string);
struct data{
  int sh,sm,ss,eh,em,es;
  bool operator<(const data& right)const{
    if(eh!=right.eh) return eh<right.eh;
    if(em!=right.em) return em<right.em;
    if(es!=right.es) return es<right.es;
    if(sh!=right.sh) return sh<right.sh;
    if(sm!=right.sm) return sm<right.sm;
    return ss<right.ss;
  }
};
int main(){
  int n,cnt,check[N],ok,flag,Max,i,j;
  int comh,comm,coms;
  string start[N],end[N],sub;
  while(1){
    cin >> n;
    vector<data> V(n);
    cnt=0;
    if(n==0) break;
    for(i=0;i<n;i++){
      cin >> start[i] >> end[i];
      check[i]=-1;
      sub=start[i].substr(0,2);
      V[i].sh=Change(sub);
      sub=start[i].substr(3,2);
      V[i].sm=Change(sub);
      sub=start[i].substr(6,2);
      V[i].ss=Change(sub);
      sub=end[i].substr(0,2);
      V[i].eh=Change(sub);
      sub=end[i].substr(3,2);
      V[i].em=Change(sub);
      sub=end[i].substr(6,2);
      V[i].es=Change(sub);
    }
    sort(V.begin(),V.end());
    for(i=0;i<n;i++){
      if(check[i]==-1){
	check[i]=i;
	comh=V[i].eh;
	comm=V[i].em;
	coms=V[i].es;
	for(j=i+1;j<n;j++){
	  if(check[j]==-1){
	    ok=0;
	    if(comh==V[j].sh){
	      if(comm==V[j].sm){
		if(coms<=V[j].ss) ok=1;
	      }
	      else if(comm<V[j].sm) ok=1;
	    }
	    else if(comh<V[j].sh) ok=1;
	    if(ok==1){
	      check[j]=i;
	      comh=V[j].eh;
	      comm=V[j].em;
	      coms=V[j].es;
	    }
	  }
	}
      }
    }
    Max=0;
    for(i=0;i<n;i++){
      Max=max(Max,check[i]);
    }
    cout << Max+1 << endl;
  }
  return 0;
}
int Change(string sub){
  int ret=0,x=1,i;
  for(i=0;i<2;i++){
    ret=ret*x+(sub[i]-'0');
    x=10;
  }
  return ret;
}

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

struct Time {
  string time;
  int type; // 0 departure, 1 arrival

  /* Time(string _time, int _type){
     time = _time;
     type = _type;
     }*/

};

bool cmp(const Time &a, const Time &b){

  if(a.time == b.time)
    return b.type < a.type;
  else
    return a.time < b.time;

}

int main(){

  int n;

  while(cin>>n&&n){

    vector<Time> times(2*n);

    for(int i=0;i<2*n;++i){

      cin>>times[i].time;
      if(i%2==0)
        times[i].type = 0;
      else
        times[i].type = 1;

 //     cout<<times[i].time<<" "<<times[i].type<<endl;

    }

    sort(times.begin(), times.end(), cmp);
 /*   for(int i=0;i<2*n;++i){

      cout<<times[i].time<<" "<<times[i].type<<endl;

    }*/

    int cnt = 0, _max = 0;

    for(int i=0;i<2*n;++i){

      if(times[i].type == 0){
        ++cnt;
      }
      else{
        --cnt;
      }

      _max = max(_max, cnt);
    }

    cout<<_max<<endl;

  }

  return EXIT_SUCCESS;
}