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>

using namespace std;

typedef long long LL;
typedef vector<int>    VI;
typedef vector<bool>   VB;
typedef vector<string> VS;

#define MP make_pair
#define PB push_back
#define ALL(x)  (x).begin(),(x).end()
#define rep(i, N)  for (int i = 0; i < (int)(N); i++)
#define REP(i, init, N)  for (int i = (init); i < (int)(N); i++)
#define DUMP( x ) cerr << #x << " = " << ( x ) << endl

int n;
VI ss, gs;

const int INF = INT_MAX / 2;

bool check(int s) {
	rep (i, gs.size()) {
		if (s >= gs[i]) {
			gs[i] = INF;
			return true;
		}
	}
	return false;
}

int main(void) {
	while (1) {
		ss.clear();
		gs.clear();
		cin >> n;
		if (n == 0) break;
		VI gts;
		rep (i, n) {
			int h, m, s;
			scanf("%d:%d:%d", &h, &m, &s);
			int stime = h * 60 * 60;
			stime += m * 60;
			stime += s;
			scanf("%d:%d:%d", &h, &m, &s);
			int gtime = h * 60 * 60;
			gtime += m * 60;
			gtime += s;
			ss.PB(stime);
			gs.PB(gtime);
		}
		sort(ALL(gs));
		reverse(ALL(gs));
		int ans = 0;
		rep (i, n) {
			if (!check(ss[i])) {
				ans++;
			}
		}
		cout << ans << endl;
	}
    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;i++){
      c+=t[i].second;
      m=max(m,c);
    }
    cout<<m<<endl;
  }
  return 0;
}

C++: #include <stdio.h>
#include <algorithm>
using namespace std;
int r[90001], n, h1, m1, s1, h2, m2, s2;
int main() {
	while (~scanf("%d", &n)) {
		if (n == 0) break;
		for (int i = 0; i <= 90000; i++) r[i] = 0;
		for (int i = 0; i < n; i++) {
			scanf("%02d:%02d:%02d %02d:%02d:%02d", &h1, &m1, &s1, &h2, &m2, &s2);
			r[h1 * 3600 + m1 * 60 + s1]++;
			r[++h2 * 3600 + m2 * 60 + s1]--;
		}
		int ret = 0, sum = 0;
		for (int i = 0; i <= 90000; i++) {
			sum += r[i];
			ret = max(ret, sum);
		}
		printf("%d\n", ret);
	}
	return 0;
}

C++: #include<iostream>
using namespace std;
int main() {
	int n, h, m, s;
	char c, d;
	while (cin >> n && n) {
		int data[86400] = {};
		for (int i = 1; i <= n; ++i) {
			cin >> h >> c >> m >> d >> s;
			data[h * 3600 + m * 60 + s]++;
			cin >> h >> c >> m >> d >> s;
			data[h * 3600 + m * 60 + s]--;
		}
		int max = 0;
		for (int i = 1; i < 86400; ++i) {
			data[i] += data[i - 1];
			if (max < data[i]) max = data[i];
		}
		cout << max << endl;
	}
	return 0;
}

C++: #include "bits/stdc++.h"
using namespace std;
typedef long long ll;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
const int INF = 1e9;
const ll LINF = 1e18;
template<class S,class T> ostream& operator << (ostream& out,const pair<S,T>& o){ out << "(" << o.first << "," << o.second << ")"; return out; }
template<class T> ostream& operator << (ostream& out,const vector<T> V){ for(int i = 0; i < V.size(); i++){ out << V[i]; if(i!=V.size()-1) out << " ";} return out; }
template<class T> ostream& operator << (ostream& out,const vector<vector<T> > Mat){ for(int i = 0; i < Mat.size(); i++) { if(i != 0) out << endl; out << Mat[i];} return out; }
template<class S,class T> ostream& operator << (ostream& out,const map<S,T> mp){ out << "{ "; for(auto it = mp.begin(); it != mp.end(); it++){ out << it->first << ":" << it->second; if(mp.size()-1 != distance(mp.begin(),it)) out << ", "; } out << " }"; return out; }

/*
 <url:>
 問題文============================================================
 =================================================================
 解説=============================================================
 ================================================================
 */

#define Day 2*60*60*24+10
int imos[Day];
int solve(int n){
    int res = 0;
    fill(imos,imos+Day,0);
    for(int i = 0; i < n;i++){
        int h,m,s; char c;
        cin >> h >> c >> m >> c >> s;
        int T = h*3600+60*m+s;
       // cout << 2*T << " ";
        imos[2*T]++;
        cin >> h >> c >> m >> c >> s;
        T = h*3600+60*m+s;
        imos[2*T]--;
       // cout << 2*T << " " << endl;
    }
    res = imos[0];
    for(int i = 1; i < Day;i++){
        imos[i] += imos[i-1];
        res = max(res,imos[i]);
    }
  //  vector<ll> x(imos,imos+Day);
   // cout << x << endl;
    return res;
}
int main(void) {
    cin.tie(0); ios_base::sync_with_stdio(false);
    int n;
    while(cin >> n,n){
        cout << solve(n) << endl;
    }
    return 0;
}

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

int main() {
  
  for(int n; cin >> n, n;) {
    int h, m, s;
    int data[86401] = {};
    for(int i=0; i<n; i++) {
      scanf("%d:%d:%d", &h, &m, &s);
      data[h*3600+m*60+s] ++;
      scanf("%d:%d:%d", &h, &m, &s);
      data[h*3600+m*60+s] --;
    }
    
    int res = 0;
    for(int i=0; i<=86400; i++) {
      data[i+1] += data[i];
      res = max(res, data[i]);
    }
    
    cout << res << endl;
  }
  
  return 0;
}