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 <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);
    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 <iostream>
#include <string>

using namespace std;
int table[90000];

void solve()
{
	int n;
	while(cin >> n, n)
	{
		while(n--)
		{
			string str1, str2;
			cin >> str1 >> str2;
			int start, end;
			start = (str1[0] - '0') * 36000 + (str1[1] - '0') * 3600 + (str1[3] - '0') * 600 + (str1[4] - '0') * 60 + (str1[6] - '0') * 10 + (str1[7] - '0');
			end = (str2[0] - '0') * 36000 + (str2[1] - '0') * 3600 + (str2[3] - '0') * 600 + (str2[4] - '0') * 60 + (str2[6] - '0') * 10 + (str2[7] - '0');
			for(int i = start; i < end; ++i)
			{
				table[i]++;
			}
		}
		int max = 0;
		for(int i = 0; i < 90000; ++i)
		{
			if(max < table[i])
			{
				max = table[i];
			}
		}
		cout << max << endl;
	}
}

int main()
{
	solve();
	return(0);
}

C++: #include<bits/stdc++.h>
#define rep(i,a) for(int i=(int)0;i<(int)a;++i)
#define rrep(i,a) for(int i=(int)a-1;i>=0;--i)
#define REP(i,a,b) for(int i=(int)a;i<(int)b;++i)
#define RREP(i,a,b) for(int i=(int)a-1;i>=b;--i)
#define pb push_back
#define eb emplace_back
#define all(x) x.begin(),x.end()
#define rall(x) x.rbegin(),x.rend()
typedef std::vector<int> vi;
typedef std::vector<std::vector<int>> vvi;
typedef std::vector<long long> vl;
typedef std::vector<std::vector<long long>> vvl;
#define out(x) cout<<x<<"\n";
using ll=long long;
constexpr ll mod = 1e9 + 7;
constexpr ll INF = 1LL << 60;

ll gcd(ll n, ll m) {
    ll tmp;
    while (m!=0) {
        tmp = n % m;
        n = m;
        m = tmp;
    }
    return n;
}

ll lcm(ll n, ll m) {
    return abs(n) / gcd(n, m)*abs(m);//gl=xy
}
 
template<class T> inline bool chmin(T& a, T b) {
    if (a > b) {
        a = b;
        return true;
    }
    return false;
}
template<class T> inline bool chmax(T& a, T b) {
    if (a < b) {
        a = b;
        return true;
    }
    return false;
}
 
using namespace std;

int n;

void solve(){
  vector<int>imos(90000+5);
  rep(i,n){
    string s,t;
    cin>>s>>t;
    int sh=(s[0]-'0')*36000+(s[1]-'0')*3600;
    int sm=(s[3]-'0')*600+(s[4]-'0')*60;
    int ss=(s[6]-'0')*10+(s[7]-'0');
    int th=(t[0]-'0')*36000+(t[1]-'0')*3600;
    int tm=(t[3]-'0')*600+(t[4]-'0')*60;
    int ts=(t[6]-'0')*10+(t[7]-'0');
    imos[sh+sm+ss]++;
    imos[th+tm+ts]--;
  }
  int ans=0;
  rep(i,9e4)imos[i+1]+=imos[i];
  rep(i,9e4)chmax(ans,imos[i]);
  cout<<ans<<"\n";
}


int main(){
    ios::sync_with_stdio(false);
    cin.tie(0);
    cout<<fixed<<setprecision(15);
    while(1){
      cin>>n;
      if(n==0)break;
      solve();
    }
    //solve();
    return 0;
}

C++: #include <cstdio>
#include <vector>
#include <algorithm>
#include <utility>
using namespace std;

typedef pair<int,int> pii;

int main(){
	int n, h1, m1, s1, h2, m2, s2;
	while(scanf("%d", &n), n){
		vector<pii> v;
		v.reserve(2 * n);

		for(int i = 0; i < n; ++i){
			scanf("%d:%d:%d%d:%d:%d", &h1, &m1, &s1, &h2, &m2, &s2);
			v.push_back(pii(h1 * 3600 + m1 * 60 + s1, 1));
			v.push_back(pii(h2 * 3600 + m2 * 60 + s2, -1));
		}
		sort(v.begin(), v.end());
		
		int ans = 0;
		int t = 0;
		for(int i = 0; i < v.size(); ++i){
			t += v[i].second;
			ans = max(ans, t);
		}
		
		printf("%d\n", ans);
	}
}

C++: #include <algorithm>
#include <climits>
#include <cmath>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <functional>
#include <iostream>
#include <map>
#include <ostream>
#include <queue>
#include <set>
#include <stack>
#include <string>
#include <vector>
#define INF 1000000000
#define rep(i,a,b) for (int i=(a);i<(b);i++)
#define rev(i,a,b) for (int i=(a)-1;i>=b;i--)
using namespace std;
typedef long long ll;
typedef pair<int, int> pii;
typedef queue<int> qi;
typedef vector<int> vi;
typedef vector<string> vs;
int dx[4] = { 0, 1, 0, -1 };
int dy[4] = { 1, 0, -1, 0 };

int main() {
	cin.tie(0);
	ios::sync_with_stdio(false);

	while(true) {
		int n;
		cin >> n;
		if(n == 0) break;

		vector<pii> vp;
		rep(i,0,n) {
			int h,m,s;
			scanf("%d:%d:%d", &h, &m, &s);
			vp.push_back(pii(h*3600 + m*60 + s, 1));
			scanf("%d:%d:%d", &h, &m, &s);
			vp.push_back(pii(h*3600 + m*60 + s, -1));
		}

		sort(vp.begin(), vp.end());
		int ans = -1, tmp = 0;
		rep(i,0,vp.size()) {
			tmp += vp[i].second;
			ans = max(ans, tmp);
		}
		cout << ans << endl;
	}

	return 0;
}