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;

//repetition
#define FOR(i,a,b) for(ll i=(a);i<(b);++i)
#define rep(i, n) for(ll i = 0; i < (ll)(n); i++)

//container util
#define all(x) (x).begin(),(x).end()

//typedef
typedef long long ll;
typedef vector<int> VI;
typedef vector<VI> VVI;
typedef vector<ll> VLL;
typedef vector<VLL> VVLL;
typedef vector<string> VS;
typedef pair<int, int> PII;
typedef pair<ll, ll> PLL;


//conversion
inline int toInt(string s) {int v; istringstream sin(s);sin>>v;return v;}
inline ll toLL(string s) {ll v; istringstream sin(s);sin>>v;return v;}
template<class T> inline string toString(T x) {ostringstream sout;sout<<x;return sout.str();}

int clacTime(string s){
  int st = toInt(s.substr(0,2)) * 10000;
  st += toInt(s.substr(3,2)) * 100;
  st += toInt(s.substr(6,2));
  return st;
}
int main(){
    ios::sync_with_stdio(false);
    cin.tie(0);
    ll n;
    while(true){
      cin >> n;
      if(n == 0) break;
      string s,e;
      VLL arr(300000,0);
      rep(i,n){
        cin >> s >> e;
        int st = clacTime(s);
        int et = clacTime(e);
        arr[st] ++;
        arr[et]--;
      }

      rep(i,arr.size()-1){
        arr[i+1] += arr[i];
      }

      ll ans = 0;
      rep(i,arr.size()){
        ans = max(arr[i],ans);
      }
      cout << ans << endl;
    }
    return 0;
}

C++: /*
 *
 *
 */

#include <bits/stdc++.h>

using namespace std;

#define LOG(...) fprintf(stderr, __VA_ARGS__)
//#define LOG(...)
#define FOR(i, a, b) for(int i = (int)(a); i < (int)(b); ++i)
#define REP(i, n) for(int i = 0; i < (int)(n); ++i)
#define ALL(a) (a).begin(), (a).end()
#define RALL(a) (a).rbegin(), (a).rend()
#define EXIST(s, e) ((s).find(e) != (s).end())
#define SORT(c) sort(ALL(c))
#define RSORT(c) sort(RALL(c))
#define SQ(n) (n) * (n)

typedef long long ll;
typedef unsigned long long ull;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
typedef vector<bool> vb;
typedef vector<int> vi;
typedef vector<pii> vpi;
typedef vector<pll> vpl;
typedef vector<ll> vll;
typedef vector<vb> vvb;
typedef vector<vi> vvi;
typedef vector<vll> vvll;



int main() {
  int n;
  int h1, h2, m1, m2, s1, s2;
  while(cin >> n, n){
    vi cnt(24 * 60 * 60, 0);
    REP(i, n){
      scanf("%2d:%2d:%2d %2d:%2d:%2d", &h1, &m1, &s1, &h2, &m2, &s2);
      int first = h1 * 60 * 60 + m1 * 60 + s1;
      int second = h2 * 60 * 60 + m2 * 60 + s2;
      FOR(t, first, second){
        cnt[t]++;
      }
    }

    cout << *max_element(ALL(cnt)) << endl;
  }
}

C++: #include <bits/stdc++.h>
#define int long long
#define pii pair<int,int>
#define FOR(i,a,b) for(int i=(a);i<(b);++i)
#define REP(i,n) FOR(i,0,n)
#define ALL(c) (c).begin(),(c).end()
#define ZERO(a) memset(a,0,sizeof(a))
#define MINUS(a) memset(a,0xff,sizeof(a))
#define MINF(a) memset(a,0x3f,sizeof(a))
#define POW(n) (1LL<<(n))
#define IN(i,a,b) (a <= i && i <= b)
using namespace std;
template <typename T> inline bool CHMIN(T& a,T b) { if(a>b) { a=b; return 1; } return 0; }
template <typename T> inline bool CHMAX(T& a,T b) { if(a<b) { a=b; return 1; } return 0; }
template <typename T> inline void SORT(T& a) { sort(ALL(a)); }
template <typename T> inline void REV(T& a) { reverse(ALL(a)); }
template <typename T> inline void UNI(T& a) { sort(ALL(a)); a.erase(unique(ALL(a)),a.end()); }
const int MOD = 1000000007;
const int INF = 0x3f3f3f3f3f3f3f3f;
const double EPS = 1e-10;
/* ---------------------------------------------------------------------------------------------------- */

int n;
int cum[24*60*60+10];

signed main() {
  cin.tie(0);
  ios_base::sync_with_stdio(false);
  cout << fixed << setprecision(10);

  while (cin >> n, n) {
    ZERO(cum);
    REP(i,n) {
      REP(j,2) {
        int hh,mm,ss;
        char c;
        cin >> hh >> c >> mm >> c >> ss;
        if (j == 0) {
          cum[hh*3600+mm*60+ss]++;
        } else {
          cum[hh*3600+mm*60+ss]--;
        }
      }
    }
    int ans = cum[0];
    REP(i,24*60*60) {
      cum[i+1] += cum[i];
      CHMAX(ans,cum[i+1]);
    }
    cout << ans << endl;
  }

  return 0;
}

C++: #include <cstdio>
#include <cstdlib>
#include <cmath>
#include <cstring>

#include <iostream>
#include <string>
#include <algorithm>
#include <vector>
#include <queue>
#include <stack>
#include <map>
#include <set>

#include <functional>
#include <cassert>

typedef long long ll;
using namespace std;

#define debug(x) cerr << #x << " = " << x << endl;


#define mod 1000000007 //1e9+7(prime number)
#define INF 1000000000 //1e9
#define LLINF 2000000000000000000LL //2e18
#define SIZE 100010

bool solve(){
  int n;
  vector<pair<int,int> > vec;
  
  scanf("%d",&n);

  if(n == 0) return false;


  for(int i=0;i<n;i++){
    int sh,sm,ss,eh,em,es;
    int s,e;

    scanf("%d:%d:%d %d:%d:%d",&sh,&sm,&ss,&eh,&em,&es);

    s = sh*3600 + sm+60 + ss;
    e = eh*3600 + em+60 + es;

    vec.push_back({s,e});
  }

  sort(vec.begin(),vec.end());

  int ans = 0;

  priority_queue<int> pq;
  
  for(int i=0;i<n;i++){
    while(pq.size() && -pq.top() <= vec[i].first) pq.pop();

    pq.push(-vec[i].second);
    
    ans = max(ans, (int)pq.size());
  }

  printf("%d\n",ans);

  return true;
}


int main(){

  while(solve());
  
  return 0;
}