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<cstring>
#include<algorithm>
using namespace std;
int k[2][10000], p[10000], n, T[3] = { 3600,60,1 }, MAX, s;
string S;
int main() {
	while (true) {
		MAX = 0;
		memset(k, 0, sizeof(k));
		cin >> n;
		if (n == 0) { break; }
		for (int i = 0; i < n; i++) {
			for (int h = 0; h < 2; h++) {
				cin >> S;
				for (int j = 0; j < 3; j++) {
					k[h][i] += T[j] * stoi(S.substr(3 * j, 2));
				}
			}
		}
		sort(k[1], k[1] + n);
		sort(k[0], k[0] + n);
		for (int i = 0; i < 2; i++) {
			for (int j = 0; j < n; j++) {
				s = 0;
				for (int l = j; l < n; l++) {
					if ((k[i][l] - k[i][j]) < 3600) {
						s++;
					}
					else {
						goto E;
					}
				}
			E:; MAX = max(s, MAX);
			}
		}
		cout << MAX << endl;
	}
}

C++: #include <stdio.h>
#include <stdlib.h>
#include <stdio.h>
#include <math.h>
#include <cctype>

#include <iostream>
#include <vector>
#include <deque>
#include <queue>
#include <map>
#include <algorithm>

using namespace std;

#define rep(i, n) for(int i = 0; i < n; i++)
#define repi(i,l,n) for(int (i)=(int)(l);(i)<(int)(n);(i)++)
#define d_arr(arr, h, w) rep(i,(h) ){ cout << "["; rep(j,(w) ) { cout << (arr)[i][j] << ", "; } cout << "]" << endl;}

typedef pair<int ,int> P;

class Train
{
    public:
        int start[3];
        int end[3];

        Train()
        {
            rep(i,3){
                start[i] = 0;
                end[i] = 0;
            }

        }
        Train(int s[3], int e[3])
        {
            rep(i,3){
                start[i] = s[i];
                end[i] = e[i];
            }
        }

        //Coordinates operator+(Coordinates p)
        //{
        //    Coordinates tmp;
        //    tmp.x = x + p.x;
        //    tmp.y = y + p.y;
        //    return tmp;
        //}

        //friend bool operator==(const Coordinates a, const Coordinates b)
        //{
        //    return (a.x == b.x && a.y == b.y);
        //}
        //friend bool operator<(const Coordinates a, const Coordinates b)
        //{
        //    return (a.x < b.x && a.y < b.y);
        //}
        //friend bool operator<=(const Coordinates a, const Coordinates b)
        //{
        //    return (a.x <= b.x && a.y <= b.y);
        //}
};



int main()
{
    int n;
    while( cin >> n, n)
    {
        vector< vector<int> > s_vec;
        vector< vector<int> > e_vec;
        rep(i,n)
        {
            vector<int> s(3);
            vector<int> e(3);
            scanf("%d:%d:%d",&s[0],&s[1],&s[2]);
            scanf("%d:%d:%d",&e[0],&e[1],&e[2]);
            s_vec.push_back(s);
            e_vec.push_back(e);
        }
        vector<int> min(3);
        vector<int> max(3);

        rep(i,3)
        {
            min[i] = s_vec[0][i];
            max[i] = e_vec[n-1][i];
        }
        int min_time = min[0]*60*60 + min[1]*60 + min[2];
        int max_time = max[0]*60*60 + max[1]*60 + max[2];
        int max_count = 0;
        //テ・ツ青?ヲツ卍づゥツ鳴禿」ツ?ォテ・ツッツセテ」ツ?療」ツ?ヲ
        for( int i = min_time; i<= max_time; i++)
        {
            int count = 0;
            int now[3];
            now[0] = i/ (60*60);
            now[1] = (i -now[0]) / 60;
            now[2] = (i -now[0]) % 60;
            //confrim
            //テ・ツ青?ヲツδ?・ツ?アテ」ツ?ォテ・ツッツセテ」ツ?療」ツ?ヲ
            rep(j,n)
            {
                int s_time = s_vec[j][0]*60*60 + s_vec[j][1]*60 + s_vec[j][2];
                int e_time = e_vec[j][0]*60*60 + e_vec[j][1]*60 + e_vec[j][2];
                if( s_time <= i && i < e_time )
                {
                    count++;
                }
            }
            if (count > max_count) { max_count = count; }
        }
        cout << max_count << endl;
    }
}

C++: #include <iostream>
#include <cstdio>
#include <algorithm>
#include <vector>

using namespace std;

int n;
int sh, sm, ss, th, m, ts;
vector<pair<int,int> > tim;

int main(){
    
    while(cin >> n, n){
        
        tim.clear();
        for(int i = 0; i < n; i++){
            scanf("%d:%d:%d %d:%d:%d", &sh, &sm, &ss, &th, &m, &ts);
            tim.push_back(make_pair(th*60*60+m*60+ts,sh*60*60+sm*60+ss));
            //cout << tim[i].second << ' ' << tim[i].first << endl;
        }
        sort(tim.begin(),tim.end());
        
        int mcnt = 0;
        for(int i = 0; i < n; i++){
            int cnt = 0;
            for(int j = i+1; j < n;j++){
                if(tim[i].first > tim[j].second) cnt++;
            }
            mcnt = max(mcnt, cnt);
        }
        cout << mcnt + 1 << endl;
    }
}

C++: #include <bits/stdc++.h>
#define PB push_back
#define MP make_pair
#define REP(i,n) for (int i=0;i<(n);i++)
#define FOR(i,a,b) for(int i=(a);i<(b);i++)
#define ALL(a) (a).begin(),(a).end()
#define MOD 100000
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef pair<int,int> P;
const int INF=1e9;
int rec(int h,int m,int s){
      return h*3600+m*60+s;
}
int cnt[60*60*24+1];
int main(){
      int n;
      while(cin>>n&&n){
            memset(cnt,0,sizeof(cnt));
            int h1,m1,s1,h2,m2,s2;
            REP(i,n){
                  scanf("%d:%d:%d %d:%d:%d",&h1,&m1,&s1,&h2,&m2,&s2);
                  cnt[rec(h1,m1,s1)]++;
                  cnt[rec(h2,m2,s2)+1]--;
            }
            int ans=0;
            REP(i,60*60*24+1){
                  if(i==0)continue;
                  ans=max(cnt[i],ans);
            }
            cout<<ans<<endl;
      }
}