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 <functional>
#include <algorithm>
#include <iostream>
#include <numeric>
#include <iomanip>
#include <utility>
#include <cstdlib>
#include <sstream>
#include <bitset>
#include <vector>
#include <cstdio>
#include <ctime>
#include <queue>
#include <deque>
#include <cmath>
#include <stack>
#include <list>
#include <map>
#include <set>

using namespace std;

typedef vector<int> vi;
typedef pair<int,int> pii;
typedef long long ll;

#define dump(x)  cerr << #x << " = " << (x) << endl
#define rep(i,n) for(int i=0;i<(n);i++)
#define all(a)  (a).begin(),(a).end()
#define pb push_back


int solve(string s){
    int ret=0;
    string tmp=s.substr(0,2);
    ret+=stoi(tmp)*60*60;
    tmp=s.substr(3,2);
    ret+=stoi(tmp)*60;
    tmp=s.substr(6,2);
    ret+=stoi(tmp);
    
    return ret;
}

int main(){
    int n;
    while(cin>>n){
        int data[100000]={};
        if(n==0)break;
        
        rep(i,n){
            string a,b;
            cin>>a>>b;
            data[solve(a)]+=1;
            data[solve(b)]-=1;
        }
        for(int i=1;i<40000;i++){
            data[i]=data[i]+data[i-1];
        }
        
        int ans=-1;
        rep(i,40000){
            ans=max(ans,data[i]);
        }
        cout<<ans<<endl;
    }
    
    return 0;
}

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

int main() {
	int n, data[6];
	int max_mini = 0;
	
	while (cin >> n) {
		if (n == 0)break;
		int x[86401] = { 0 };
		for (int i = 0; i < n; i++) {
			scanf_s("%d:%d:%d %d:%d:%d",&data[0],&data[1],&data[2],&data[3],&data[4],&data[5]);
			x[data[0] * 3600 + data[1] * 60 + data[2]]++;
			x[data[3] * 3600 + data[4] * 60 + data[5]]--;
			if (max_mini < data[3] * 3600 + data[4] * 60 + data[5])
				max_mini = data[3] * 3600 + data[4] * 60 + data[5];
		}
		int ans = 0, cnt = 0;
		for (int i = 0; i <= max_mini; i++) {
			cnt += x[i];
			ans = max(ans, cnt);
		}
		cout << ans << endl;
	}
	return 0;
	
}

C++: #include<iostream>
#include<algorithm>
#include<vector>
#include<queue>
#include<deque>
#include<map>
#include<set>
#include<string>
#include<sstream>
#include<cstdio>
#include<cmath>
#include<cstring>
#include<cctype>
#include<climits>
using namespace std;
#define REP(i, j) for(int i = 0; i < j; i++)
#define FOR(i, j, k) for(int i = j; i < k; i++)
#define P pair<int, int>
const int INF = INT_MAX / 2;

int Inp(string str){
    stringstream ss(str);
    int ret = 0, n;
    char tmp;
    ss >>n >>tmp;
    ret += (n * 3600);
    ss >>n >>tmp;
    ret += (n * 60);
    ss >>n;
    ret += n;
    return ret;
}

int main(){
    int n;
    while(cin >>n && n){
        vector<P> v;
        REP(i, n){
            string str;
            cin >>str; v.push_back( P(Inp(str), 1) );
            cin >>str; v.push_back( P(Inp(str), 0) );
        }
        sort(v.begin(), v.end());

        int t = 0, ans = 0;
        REP(i, v.size()){
            int time = v[i].first;
            int io = v[i].second;
            if(io == 1){
                if(t == 0){
                    ans++;
                } else{
                    t--;
                }
            } else{
                t++;
            }
        }
        cout <<ans <<endl;
    }
    return 0;
}

C++: #include <bits/stdc++.h>
using ll = long long;
using namespace std;
#define rep(i,n) for(int i=0, i##_len=(int)(n); i<i##_len; i++)
#define reps(i,n) for(int i=1 , i##_len=(int)(n);i<=i##_len;i++)
#define rrep(i,n) for(int i=((int)(n)-1);i>=0;i--)
#define rreps(i,n) for(int i=((int)(n));i>0;i--)
#define all(x) (x).begin(), (x).end()
#define F first
#define S second
#define mp make_pair
#define pb push_back
#define solve(a) ((a)?"Yes":"No")
typedef vector<long long> V;
typedef vector<V> VV;
typedef pair<long long , long long> P;
typedef vector<P> VP;
template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return 1;} return 0;}
template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return 1;} return 0;}
const long long INFLL = 1LL<<62;
const int INF = 1<<30;
const double PI=acos(-1);
int trans(char s){
	return (s-'0');
}
int main(){
	int n;
	int ans=0;
	vector<pair<string,string>>data;
	vector<int>table;
	pair<int,int> hash;
	while(1){
	cin >>n;
	data.clear();
	table.clear();
	if(n==0){
		break;
	}
	ans=0;
	table.resize(86410);
	table.assign(86410,0);
	data.resize(n);
	rep(i,n){
		hash=mp(0,0);
		cin>>data[i].F>>data[i].S;//01:34:67
		hash.F+=trans(data[i].F[7]);
		hash.F += 10*trans(data[i].F[6]);
		hash.F += 60*trans(data[i].F[4]);
		hash.F += 600*trans(data[i].F[3]);
		hash.F += 3600*trans(data[i].F[1]);
		hash.F += 36000*trans(data[i].F[0]);

		hash.S += trans(data[i].S[7]);
		hash.S += 10 * trans(data[i].S[6]);
		hash.S += 60 * trans(data[i].S[4]);
		hash.S += 600 * trans(data[i].S[3]);
		hash.S += 3600 * trans(data[i].S[1]);
		hash.S += 36000 * trans(data[i].S[0]);
		table[hash.F]++;
		table[hash.S]--;
	}
	rep(i,86402){
		table[i+1]+=table[i];
		chmax(ans,table[i]);
	}

	cout<<ans<<endl;
	}
}