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 <functional>
#include <algorithm>
#include <iostream>
#include <numeric>
#include <iomanip>
#include <utility>
#include <cstdlib>
#include <sstream>
#include <bitset>
#include <vector>
#include <cstdio>
#include <ctime>
#include <queue>
#include <deque>
#include <cmath>
#include <stack>
#include <list>
#include <map>
#include <set>

using namespace std;

typedef vector<int> vi;
typedef pair<int,int> pii;
typedef long long ll;

#define dump(x)  cerr << #x << " = " << (x) << endl
#define rep(i,n) for(int i=0;i<(n);i++)
#define all(a)  (a).begin(),(a).end()
#define pb push_back



int main(){
    int n;
    while(cin>>n){
        int data[100000]={};
        if(n==0)break;
        
        rep(i,n){
            char ch;
            int a,aa,aaa,b,bb,bbb;
            cin>>a>>ch>>aa>>ch>>aaa>>b>>ch>>bb>>ch>>bbb;
            data[a*60*60+aa*60+aaa]+=1;
            data[b*60*60+bb*60+bbb]-=1;
        }
        for(int i=1;i<90000;i++){
            data[i]=data[i]+data[i-1];
        }
        
        int ans=-1;
        rep(i,90000){
            ans=max(ans,data[i]);
        }
        cout<<ans<<endl;
    }
    
    return 0;
}

C++: #include <iostream>
#include <cstdio>
#include <set>
using namespace std;
int main()
{
  for(;;){
    int n;
    cin >> n;
    if(n == 0) break;
    multiset<int> slist,elist;
    for(int i=0; i<n; i++){
      int h1,h2,m1,m2,s1,s2;
      scanf("%d:%d:%d %d:%d:%d",&h1,&m1,&s1,&h2,&m2,&s2);
      int s = h1 * 3600 + m1 * 60 + s1;
      slist.insert(s);
      int e = h2 * 3600 + m2 * 60 + s2;
      elist.insert(e);
    }
    int ret = 0, count = 0;
    multiset<int>::iterator its = slist.begin(), ite = elist.begin();
    while(its != slist.end()){
      if((*its) < (*ite)){
        count++;
        its++;
        if(count > ret) ret = count;
      }else{
        count--;
        ite++;
      }
    }
    cout << ret << endl;
  }
  return 0;
}

C++: #include<iostream>
#include<iomanip>
#include<algorithm>
#include<bitset>
#include<cctype>
#include<cmath>
#include<cstdio>
#include<cstring>
#include<functional>
#include<limits>
#include<list>
#include<map>
#include<set>
#include<stack>
#include<string>
#include<sstream>
#include<queue>
#include<vector>
using namespace std;
 
#define MOD 1000000007
#define INF 0x3f3f3f3f
#define INFL 0x3f3f3f3f3f3f3f3fLL
 
int main() {
    int s[10000], g[10000], f[10000]={}, hhs, mms, sss, hhg, mmg, ssg, cnt = 1;
    for(int n;cin>>n&&n;){
        
        
        for (int i = 0; i < n; i++) {
            char c;
            cin >> hhs >> c >> mms >> c >> sss >> hhg >> c >> mmg >> c >> ssg;
 
            s[i] = 3600 * hhs + 60 * mms + sss;
            g[i] = 3600 * hhg + 60 * mmg + ssg;
        }
		
		for(int i=0;i<n-1;i++)
			for(int j=n-1;j>i;j--)
				if(s[j-1]>s[j]){
					int tmp=s[j];
					s[j]=s[j-1];
					s[j-1]=tmp;
					tmp=g[j];
					g[j]=g[j-1];
					g[j-1]=tmp;
				}
		
		
		
        for (int i = 1; i < n; i++) {
            for (int j = 0; j < i;) {
                //cout << "j" << endl;
                if (f[j] == 1) { j++; continue; }
                if (s[i] >= g[j]) {
                    f[j] = 1;
                    break;
                }
                j++;
                if (j == i)cnt++;
            }
            //cout << "i" << endl;
        }
        //cout << "h" << endl;
        cout << cnt << endl;
        cnt = 1;
 
    }
    return 0;
}

C++: //http://judge.u-aizu.ac.jp/onlinejudge/description.jsp?id=2013
//大崎
#include <bits/stdc++.h>
#if LOCAL
#include "dump.hpp"
#else
#define dump(...)
#endif
using namespace std;
using ll=long long;
const ll LINF = 0x1fffffffffffffff;
#define FOR(i,a,b) for(ll i=(a);i<(b);++i)
#define REP(i,n) FOR(i,0,n)
template<class T>bool chmax(T &a, const T &b) {if (a<b) { a=b; return 1; } return 0;}
template<class T>bool chmin(T &a, const T &b) {if (b<a) { a=b; return 1; } return 0;}

std::vector<std::string> split(const std::string& input, char delimiter){
  std::istringstream stream(input);
  std::string field;
  std::vector<std::string> result;
  while (std::getline(stream, field, delimiter)) {
    result.push_back(field);
  }
  return result;
}

ll solve(){
  vector<vector<vector<ll>>> hms(24+1,vector<vector<ll>>(60+1, vector<ll>(60+1)));
  ll n; cin>>n;
  if (n==0)return -1;
  REP(i,n){
    string s,e; cin>>s>>e;
    auto gett =[](const string& is){
      vector<ll> ret;
      auto lst=split(is,':');
      REP(ii,3){
        int v=std::atoi(lst.at(ii).c_str());  
        ret.push_back(v);
      }
      return ret;
    };
    auto stt = gett(s);
    auto edd = gett(e);
    // dump(stt);
    // dump(edd);
    hms[stt[0]][stt[1]][stt[2]] += 1;

    // edd[2] += 1;
    // if(edd[2]==60){
    //   edd[2]=0;
    //   edd[1]+=1;
    //   if(edd[1]==60){
    //     edd[1]=0;
    //     edd[0]+=1;
    //   }
    // }
    hms[edd[0]][edd[1]][edd[2]] -= 1;
  }

  ll v= 0;
  ll ans=0;
  REP(h,24){
    REP(m,60){
      REP(s,60){
        v += hms[h][m][s];
        chmax(ans,v);
      }
    }
  }
  cout<<ans<<endl;
  return ans;
}
int main() {
#if LOCAL&01
  //std::ifstream in("./test/sample-1.in");
  std::ifstream in("./input.txt");
  std::cin.rdbuf(in.rdbuf());
#else
  cin.tie(0);
  ios::sync_with_stdio(false);
#endif
  while(solve()!=-1){
  }
  return 0;
}