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 <utility>
#define REP(i,n) for(int i=0;i<(n);i++)
using namespace std;

int main()
{
  while(1){
    int n;
    scanf("%d", &n);
    if(n == 0) break;
    int ans = 1;
    pair<bool,int> train[n];
    REP(i,n)
      train[i].second = -1;
    train[0].first = false;
    pair<int,int> time[n];
    REP(i,n){
      int h, m, s;
      scanf("%d:%d:%d", &h, &m, &s);
      time[i].first = h*3600 + m*60 + s;
      scanf("%d:%d:%d", &h, &m, &s);
      time[i].second = h*3600 + m*60 + s;
    }
    train[0].second = time[0].second;
    REP(i,24*3600){
      REP(j,ans)
        if(train[j].second == i){
          train[j].first = true;
          train[j].second = -1;
        }
      for(int j = 1; j < n; j++){
        if(time[j].first == i){
          bool flag = false;
          REP(k,ans){
            if(train[k].first){
              flag = true;
              train[k].first = false;
              train[k].second = time[j].second;
              break;
            }
          }
          if(!flag){
            train[ans].first = false;
            train[ans].second = time[j].second;
            ans++;
          }
        }
      }
    }
    cout << ans << endl;
  }
}

C++: #include <iostream>

using namespace std;

#define N 86410

int max(int a,int b){
	if(a>=b)return a;
	else return b;
}

int changeTime(int h,int m,int s){
	return 3600*h+60*m+s;
}

int main(){

	int n;

	int data[N];
	
	while(cin>>n){

		int h,m,s;
		char tmp;
		int ans=0;
		for(int i=0;i<N;i++)data[i]=0;
		for(int i=0;i<n;i++){
			cin>>h>>tmp>>m>>tmp>>s;

			data[changeTime(h,m,s)]++;

			cin>>h>>tmp>>m>>tmp>>s;
			data[changeTime(h,m,s)]--;
		}

		for(int i=1;i<N;i++){
			data[i] += data[i-1];
			ans = max(data[i],ans);
		}

		cout<<ans<<endl;
	}

	return 0;
}

C++: #include <algorithm>
#include <climits>
#include <cmath>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <functional>
#include <iostream>
#include <map>
#include <ostream>
#include <queue>
#include <set>
#include <stack>
#include <string>
#include <vector>
#define INF 1000000000
#define rep(i,a,b) for (int i=(a);i<(b);i++)
#define rev(i,a,b) for (int i=(a)-1;i>=b;i--)
using namespace std;
typedef long long ll;
typedef pair<int, int> pii;
typedef queue<int> qi;
typedef vector<int> vi;
typedef vector<string> vs;
int dx[4] = { 0, 1, 0, -1 };
int dy[4] = { 1, 0, -1, 0 };

int t[87000];

int main() {
	cin.tie(0);
	ios::sync_with_stdio(false);

	while(true) {
		int n;
		cin >> n;
		if(n == 0) break;

		rep(i,0,87000) t[i] = 0;
		rep(i,0,n) {
			int h,m,s;
			scanf("%d:%d:%d", &h, &m, &s);
			t[h*3600 + m*60 + s]++;
			scanf("%d:%d:%d", &h, &m, &s);
			t[h*3600 + m*60 + s]--;
		}

		int ans = -1, tmp = 0;
		rep(i,0,87000) {
			tmp += t[i];
			if(ans < tmp) ans = tmp;
		}
		cout << ans << endl;
	}
	return 0;
}

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

using namespace std;

int main(void){
	while(1){
		int n; cin >> n;
		if(!n) break;

		vector<pair<string, string> > table(n);
		for(int i=0; i<n; i++){
			cin >> table[i].first >> table[i].second;
		}

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

		int ans = 0;
		for(int i=0; i<table.size(); i++){
			string end = table[i].second;
			ans++;
			for(int j=i+1; j<table.size(); j++){
				if(end <= table[j].first){
					end = table[j].second;
					table.erase(table.begin()+j);
					j--;
				}
			}
		}
		cout << ans << endl;
	}
}

C++: #include <bits/stdc++.h>
#define FOR(i,a,b) for(int i=(a);i<(b);i++)
#define REP(i,n) for(int i=0;i < (n);i++)
#define ALL(obj) (obj).begin(),(obj).end()
#define SCANF(i) int i;scanf("%d",&i)
using namespace std;
using P = pair<int,int>;
const long long INF = 1LL << 60;
const int IINF=100000000;
const int MOD = (int)1e9 + 7;
typedef long long ll;
//約数列挙
vector<long long> divisor(long long n) {
    vector<long long> ret;
    for (long long i = 1; i * i <= n; i++) {
        if (n % i == 0) {
            ret.push_back(i);
            if (i * i != n) ret.push_back(n / i);
        }
    }
    //sort(ret.begin(), ret.end()); // 昇順に並べる
    return ret;
}
vector<int> dx={1,0,-1,0};vector<int> dy={0,-1,0,1};

signed main () {
    int n;
    while(cin>>n){
        if(n==0)break;
        vector<int> list(24*3600 + 60 * 60 + 100,0);
        REP(i,n){
            string start;cin >> start;
            ll stime = ((start[0] - '0') * 10 + (start[1] - '0')) * 3600
                       +  ((start[3] - '0') * 10 +(start[4] - '0')) * 60
                       + ((start[6] - '0') * 10 + (start[7] - '0'));
            string endd;cin >> endd;
            ll etime = ((endd[0] - '0') * 10 + (endd[1] - '0')) * 3600
                       +  ((endd[3] - '0') * 10 +(endd[4] - '0')) * 60
                       + ((endd[6] - '0') * 10 + (endd[7] - '0'));
            list[stime]+=1;list[etime]-=1;
        }
        FOR(j,1,24*3600 + 60 * 60 + 100){
            list[j] += list[j-1];
        }
        cout << *max_element(ALL(list)) << endl;
    }
}