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 <cstdio>
#include <cmath>
#include <cstdio>
#include <cstring>
#include <string>
#include <vector>
#include <set>
#include <map>
#include <stack>
#include <queue>
#include <algorithm>

#define CH(N,A,B) (A<=N&&N<B)
#define REP(i,a,b) for(int i=a;i<b;i++)
#define RREP(i,a,b) for(int i=(b-1);a<=i;i--)

using namespace std;

int d[10000000], n, hhS, mmS, ssS, hhG, mmG, ssG;

int main() {
  while(1){
    cin>>n;
    if(n==0) break;
    REP(i,0,24*60*60+2) d[i] = 0;
    REP(i,0,n){
      scanf("%d:%d:%d %d:%d:%d", &hhS, &mmS, &ssS, &hhG, &mmG, &ssG);
      d[hhS*(60*60) + mmS*60 + ssS]++;
      d[hhG*(60*60) + mmG*60 + ssG]--;
      //test
      //cout<<"hhS "<<hhS<<", mmS "<<mmS<<", ssS "<<ssS<<endl;
    }
    int ans = 0;
    REP(i,1,24*60*60+2){
      d[i] += d[i-1];
      ans = max(ans, d[i]);
    }
    cout<<ans<<endl;
  }
  return 0;
}

C++: #include<iostream>
#include<iomanip>
#include<algorithm>
#include<vector>
#include<string>
#include<map>
#include<iostream>
#include<iomanip>
#include<algorithm>
#include<string>
#include<map>
#include<cmath>
#include<queue>	
#include<functional>
#include<climits>

using namespace std;

//define
#define ALL(a) a.begin(),a.end()
#define REP(i,n) for(int i=0;i<n;i++)
#define RREP(i,n) for(int i=n-1;i>=0;i--)
#define debug(x) if(1)cout<<#x<<":"<<x<<endl;
#define DEBUG(x) if(1)cout<<#x<<":"<<x<<endl;
#define ll long long
#define pb push_back
#define PB push_back
#define lb lower_bound
#define LB lower_bound
#define ub upper_bound
#define UB upper_bound


//constant
const int MOD = 1000000007;
const int INF = INT_MAX / 3 - 1;
const double EPS = 1e-9;
const int dx4[4] = { 1,0,-1,0 };
const int dy4[4] = { 0,1,0,-1 };

//typedef
typedef vector<int> vi;
typedef vector<vector<int>> vvi;
typedef pair<int, int> pii;


int main() {
	int n;
	while (cin >> n, n) {
		vector<pii> times(2*n);
		string buf;
		REP(i,n)
			REP(j, 2) {
			cin >> buf;
			times[2 * i + j].first = stoi(buf.substr(0, 2)) * 60 * 60 + stoi(buf.substr(3, 2)) * 60 + stoi(buf.substr(6, 2));
			times[2 * i + j].second = j;
		}
		sort(ALL(times),
			[](pii lef, pii rig) {
			return lef.first < rig.first ||
				lef.first == rig.first && lef.second>rig.second;
		});
		int count = 0;
		int stopping = 0;
		REP(i, 2 * n) {
			if (times[i].second)
				stopping++;
			else if (stopping > 0)
				stopping--;
			else
				count++;
		}
		cout << count << endl;
	}
	return 0;
}

C++: #include <iostream>
#include <algorithm>
#include <string>
#include <vector>
#include <cstdio>
#include <cmath>
#include <cstdlib>
#include <cstring>
#include <stack>
#include <queue>
#include <set>
#include <map>
#include <unordered_map>
#include <ctime>
#include <list>
#include <numeric>
#include <utility>
#include <ctime>
#define INF 1000000000
#define LINF 9000000000000000000
#define mod 1000000007
 
#define rep(i,n) for(int i=0;i<int(n);i++)
#define REP(i,a,b) for(int i=(a);i<int(b);i++)
#define all(x) (x).begin(),x.end()
#define pb push_back
#define mp make_pair
#define MOD(x) (x%(mod))
 
using namespace std;
 
typedef long long ll;
typedef unsigned long long ull;
typedef vector<int> vi;
typedef pair<int,int> pi;
 
int dx[4]={1,0,-1,0};
int dy[4]={0,1,0,-1};
bool debug=false;
 
/*---------------------------------------------------*/

void solve(int n){
  int h,m,s;
  int imos[86405];
  rep(i,86405)imos[i]=0;
  rep(i,n){
    scanf("%d:%d:%d",&h,&m,&s);
    imos[h*3600+m*60+s]++;
    scanf("%d:%d:%d",&h,&m,&s);
    imos[h*3600+m*60+s]--;
  }
  REP(i,1,86405)imos[i]+=imos[i-1];
  int ans=0;
  rep(i,86405){
    ans=max(ans,imos[i]);
  }
  cout<<ans<<endl;
}

int main(){
  int n;
  while(cin>>n){
    if(n==0)break;
    solve(n);
  }
  return 0;
}

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

const int TIME = 100000;
int data[TIME];

int main(){
	cin.tie(0);
	ios::sync_with_stdio(false);
	
	int n;
	while(cin >> n && n){
		for(int i = 0; i < TIME; ++i){
			data[i] = 0;
		}
		
		int a, b, c;
		for(int i = 0; i < n; ++i){
			scanf("%d:%d:%d", &a, &b, &c);
			data[a * 60 * 60 + b * 60 + c] ++;
			
			scanf("%d:%d:%d", &a, &b, &c);
			data[a * 60 * 60 + b * 60 + c] --;
		}
	
		int ans = 0;
		for(int i = 0; i < TIME; ++i){
			if(i > 0)
				data[i] += data[i - 1];
			ans = max(ans, data[i]);
		}
		
		cout << ans << endl;
	}
	return 0;
}

C++: // AOJ 2013

#include <iostream>
#include <cstdio>

using namespace std;

int data[24][60][60];

int main(void)
{
	int n;
	while (cin >> n, n){
		for (int i = 0; i < 24; i++){
			for (int j = 0; j < 60; j++){
				for (int k = 0; k < 60; k++){
					data[i][j][k] = 0;
				}
			}
		}

		int s[3], e[3];
		for (int i = 0; i < n; i++){
			scanf("%d:%d:%d %d:%d:%d", &s[0], &s[1], &s[2], &e[0], &e[1], &e[2]);
			int h = s[0], m = s[1], sec = s[2];
			data[h][m][sec] += 1;
			while (1){
				if (h == e[0] && m == e[1] && sec == e[2]){
					data[h][m][sec]--;
					break;
				}
				sec++;
				if (sec == 60){
					m++;
					sec = 0;
				}
				if (m == 60){
					h++;
					m = 0;
				}
				data[h][m][sec] += 1;
			}
		}
/*
		for (int i = 0; i < 24; i++){
			for (int j = 0; j < 60; j++){
				int cnt = 0;
				for (int k = 0; k < 60; k++){
					cnt = max(cnt, data[i][j][k]);
				}
				cout << cnt << " ";
			}
			puts("");
		}
*/
		int ret = 0;
		for (int i = 0; i < 24; i++){
			for (int j = 0; j < 60; j++){
				for (int k = 0; k < 60; k++){
					ret = max(ret, data[i][j][k]);
				}
			}
		}
		cout << ret << endl;
	}

	return 0;
}