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 <functional>
#include <vector>
#include <utility>
#include <cstring>
#include <iomanip>
#include <numeric>
#include <cmath>
#include <cassert>
using namespace std;
using ll = long long;
const int INF = 1<<30;
const int MOD = 1e9 + 7;
int n;
int calc(const string &s)
{
    int res = 0;
    // res += 100 * atoi(s.substr(0, 2).c_str());
    // res += 10 * atoi(s.substr(3, 2).c_str());
    // res += atoi(s.substr(6).c_str());
    res += 3600 * stoi(s.substr(0, 2));
    res += 60 * stoi(s.substr(3, 2));
    res += stoi(s.substr(6));
    return res;
}
signed main(void)
{
    while(cin >> n, n)
    {
        vector<int> cnt(100000, 0);
        for(int i = 0; i < n; i++)
        {
            string s, t; cin >> s >> t;
            cnt[calc(s)]++;
            cnt[calc(t)]--;
        }
        int ans = 1;
        for(int i = 1; i < cnt.size(); i++)
        {
            cnt[i] += cnt[i - 1];
            ans = max(ans, cnt[i]);
        }
        cout << ans << endl;
    }
    return 0;
}

C++: #include <bits/stdc++.h>
using namespace std;
int time(string s){
  return (s[0] - '0') * 36000 + (s[1] - '0') * 3600 + (s[3] - '0') * 600 + (s[4] - '0') * 60 + (s[6] - '0') * 10 + (s[7] - '0');
}
int main(){
  while (1){
    int n;
    cin >> n;
    if (n == 0){
      break;
    }
    vector<string> s(n), t(n);
    for (int i = 0; i < n; i++){
      cin >> s[i] >> t[i];
    }
    vector<int> a(n), b(n);
    for (int i = 0; i < n; i++){
      a[i] = time(s[i]);
      b[i] = time(t[i]);
    }
    vector<int> d(86400, 0);
    for (int i = 0; i < n; i++){
      d[a[i]]++;
      d[b[i]]--;
    }
    for (int i = 1; i < 86400; i++){
      d[i] += d[i - 1];
    }
    int ans = 0;
    for (int i = 0; i < 86400; i++){
      ans = max(ans, d[i]);
    }
    cout << ans << endl;
  }
}

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

typedef long long ll;
typedef unsigned long long ull;
typedef pair<ll, ll> P;

#define fi first
#define se second
#define repl(i,a,b) for(ll i=(ll)(a);i<(ll)(b);i++)
#define rep(i,n) repl(i,0,n)
#define each(itr,v) for(auto itr:v)
#define pb push_back
#define all(x) (x).begin(),(x).end()
#define dbg(x) cout<<#x"="<<x<<endl
#define mmax(x,y) (x>y?x:y)
#define mmin(x,y) (x<y?x:y)
#define maxch(x,y) x=mmax(x,y)
#define minch(x,y) x=mmin(x,y)
#define uni(x) x.erase(unique(all(x)),x.end())
#define exist(x,y) (find(all(x),y)!=x.end())
#define bcnt __builtin_popcount

#define INF INT_MAX/3

int n;
int imos[111111];

int main(){
	cin.sync_with_stdio(false);
  while(1){
    cin>>n;
    if(n==0)break;
    memset(imos,0,sizeof(imos));
    rep(i,n){
      string s,t;
      cin>>s>>t;
      int start=stoi(s.substr(0,2))*60*60+stoi(s.substr(3,2))*60+stoi(s.substr(6,2));
      int end=stoi(t.substr(0,2))*60*60+stoi(t.substr(3,2))*60+stoi(t.substr(6,2));
      imos[start]+=1;
      imos[end]-=1;
      //dbg(start); dbg(end);
    }
    rep(i,100000)imos[i+1]+=imos[i];
    cout<<*max_element(imos,imos+100000)<<endl;
  }
	return 0;
}

C++: //include
//------------------------------------------
#include <vector>
#include <list>
#include <map>
#include <set>
#include <deque>
#include <stack>
#include <bitset>
#include <algorithm>
#include <functional>
#include <numeric>
#include <utility>
#include <sstream>
#include <iostream>
#include <iomanip>
#include <cstdio>
#include <cmath>
#include <cstdlib>
#include <cctype>
#include <string>
#include <cstring>
#include <ctime>
#include <climits>
#include <queue>

using namespace std;

//typedef
//------------------------------------------
typedef vector<int> VI;
typedef vector<VI> VVI;
typedef vector<string> VS;
typedef pair<int, int> PII;
typedef long long LL;

//container util
//------------------------------------------
#define ALL(a)  (a).begin(),(a).end()
#define RALL(a) (a).rbegin(), (a).rend()
#define PB push_back
#define MP make_pair
#define SZ(a) int((a).size())
#define EACH(i,c) for(typeof((c).begin()) i=(c).begin(); i!=(c).end(); ++i)
#define EXIST(s,e) ((s).find(e)!=(s).end())
#define SORT(c) sort((c).begin(),(c).end())

//repetition
//------------------------------------------
#define FOR(i,a,b) for(int i=(a);i<(b);++i)
#define REP(i,n)  FOR(i,0,n)

//constant
//--------------------------------------------
const double EPS = 1e-10;
const double PI  = acos(-1.0);

int main(){
  int N;
  while(cin >> N, N){
	vector<PII> tms;
	REP(i,N){
	  int h[2], m[2], s[2];
	  scanf("%2d:%2d:%2d", &h[0], &m[0], &s[0]);
	  scanf("%2d:%2d:%2d", &h[1], &m[1], &s[1]);
	  tms.PB(MP(h[0]*60*60+m[0]*60+s[0], h[1]*60*60+m[1]*60+s[1]));
	}
	SORT(tms);
	int ans = 1;
	REP(i,N){
	  int s = -1, e = 60*60*60, j;
	  for(j=i;j<N;++j){
		if(e <= s) break;
		if(e <= tms[j].first) break;
		if(tms[j].second <= s) break;
		s = max(s, tms[j].first);
		e = min(e, tms[j].second);
	  }
	  ans = max(ans, j - i);
	}
	cout << ans << endl;
  }  
  
  return 0;
}