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

// ?????¬???????????¬??????
#pragma region MACRO
#define P(x) cout << (x) << endl
#define p(x) cout << (x)
#define PED cout << "\n"
#define rep(i,n) for(int i=0; i<(int)n; ++i)
#define REP(i,x,n) for(int i=x; i<(int)n; ++i)
#define repi(i,n) for(int i=0; i<=(int)n; ++i)
#define REPI(i,x,n) for(int i=x; i<=(int)n; ++i)
#define ILP while(true)
#define FOR(i,c) for(__typeof((c).begin())!=(c).begin(); i!=(c).end(); ++i)
#define ALL(c) (c).begin(), (c).end()
#define mp make_pair
#pragma endregion

// ???
#pragma region TYPE_DEF
typedef long long ll;
typedef pair<int, int> pii;
typedef pair<string, string> pss;
typedef pair<string, int> psi;
typedef pair<int, string> pis;
typedef vector<int> vi;
typedef vector<double> vd;
typedef vector<long double> vld;
typedef vector<long> vl;
typedef vector<long long> vll;
typedef vector<string> vs;
#pragma endregion

// Effective std
#pragma region ESTD
template<typename C, typename T> int count(C& c, T t) { return count(ALL(c), t); }
template<typename C, typename F> int count_if(C& c, F f) { return count_if(ALL(c), f); }
template<typename C, typename T> void erase(C& c, T t) { remove(ALL(c), t), c.end(); }
template<typename C> void remove(vector<C>& c, unsigned int index) { c.erase(c.begin()+index); }
template<typename C, typename T, typename U> void replace(C& c, T t, U u) { replace(ALL(c), t, u); }
template<typename C, typename F, typename U> void replace_if(C& c, F f, U u) { (ALL(c), f, u); }
template<typename C> void reverse(C& c) { reverse(ALL(c)); }
template<typename C> void sort(C& c) { sort(ALL(c)); }
template<typename C, typename Pred> void sort(C& c, Pred p) { sort(ALL(c), p); }
#pragma endregion

// ?????°
#pragma region CONST_VAL
constexpr int PI = (2*acos(0.0));
constexpr int EPS = (1e-9);
constexpr int MOD = (int)(1e9+7);
constexpr int INF = 100000000;
#pragma endregion

#define int long long

int sum[86401];

signed main()
{
    int n;
    while(cin>>n, n) {
        memset(sum, 0, sizeof(sum));
        signed h, m, s, h1, m1, s1;
        for(int i=0; i<n; ++i) {
            scanf("%d:%d:%d%d:%d:%d", &h, &m, &s, &h1, &m1, &s1);
            sum[h*3600+m*60+s]++;
            sum[h1*3600+m1*60+s1]--;
        }

        int Max = 0;
        for(int i=0; i<86401; ++i) {
            if(i>0) sum[i] += sum[i-1];
            Max = max(Max, sum[i]);
        }
        cout << Max << endl;
    }
    return 0;
}

C++: #include<iostream>
#include<iomanip>
#include<algorithm>
#include<bitset>
#include<cctype>
#include<cmath>
#include<cstdio>
#include<cstring>
#include<functional>
#include<limits>
#include<list>
#include<map>
#include<set>
#include<stack>
#include<string>
#include<sstream>
#include<queue>
#include<vector>
using namespace std;
 
#define MOD 1000000007
#define INF 0x3f3f3f3f
#define INFL 0x3f3f3f3f3f3f3f3fLL
 
int main() {
    int s[10001], g[10001], f[10001]={}, hhs, mms, sss, hhg, mmg, ssg, cnt = 1,n;
    while(1){
        cin>>n;
        if(n==0)break;
        for (int i = 0; i < n; i++) {
            char c;
            cin >> hhs >> c >> mms >> c >> sss >> hhg >> c >> mmg >> c >> ssg;
 
            s[i] = 3600 * hhs + 60 * mms + sss;
            g[i] = 3600 * hhg + 60 * mmg + ssg;
        }
		
		for(int i=0;i<n-1;i++){
			for(int j=n-1;j>i;j--){
				if(s[j-1]>s[j]){
					int tmp=s[j];
					s[j]=s[j-1];
					s[j-1]=tmp;
					tmp=g[j];
					g[j]=g[j-1];
					g[j-1]=tmp;
				}
			}
		}
		
		
        for (int i = 1; i < n; i++) {
            for (int j = 0; j < i;) {
                //cout << "j" << endl;
                if (f[j] == 1) { j++; continue; }
                if (s[i] >= g[j]) {
                    f[j] = 1;
                    break;
                }
                j++;
                if (j == i)cnt++;
            }
            //cout << "i" << endl;
        }
        //cout << "h" << endl;
        cout << cnt << endl;
        cnt = 1;
 
    }
    return 0;
}

C++: #include<iostream>
#include<cmath>
#include<cstdio>
#include<algorithm>
#include<vector>
#include<cstring>
#include<queue>

using namespace std;

#define INF 999999999

int tim[24*60*60];

int main(){
	int i, j, k, n, ts, tg;
	int ans;
	string s, g;
	while(1){
		cin >> n;
		if(!n)break;
		for(i=0;i<24*60*60;i++) tim[i]=0;
		ans = 0;
		for(i=0;i<n;i++){
			cin >> s >> g;
			ts = ((s[0]-'0')*10+(s[1]-'0'))*60*60
			+ ((s[3]-'0')*10+(s[4]-'0'))*60
			+ (s[6]-'0')*10+(s[7]-'0');
			tg = ((g[0]-'0')*10+(g[1]-'0'))*60*60
			+ ((g[3]-'0')*10+(g[4]-'0'))*60
			+ (g[6]-'0')*10+(g[7]-'0');
			for(j=ts;j<tg;j++) tim[j]++;
		}
		for(i=0;i<24*60*60;i++)if(ans<=tim[i]) ans=tim[i];
		cout << ans << endl;
	}
	return 0;
}