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<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,tmp;
    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;
		//	cout << s[i] << ' ' << g[i] << endl;
        }
		
		for(int i=0;i<n-1;i++){
			for(int j=n-1;j>i;j--){
				if(s[j-1]>s[j]){
					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 = 0; i < n; i++)cout << s[i] << ' ' << g[i] << endl;
		
        for (int i = 1; i < n; i++) {
            for (int j = 0; j < i;) {
               
                if (f[j] == 1) { j++; continue; }
                if (s[i] >= g[j]) {
                    f[j] = 1;
                    break;
                }
                j++;
                if (j == i)cnt++;
            }
        
		//	cout << cnt << endl;
        }
        
        cout << cnt << endl;
        cnt = 1;
		f[10001]={};
    }
    return 0;
}

C++: #include <bits/stdc++.h>

using namespace std;
typedef long long ll;
typedef vector<int> VI;
typedef vector<VI> VVI;
typedef vector<ll> VL;
typedef vector<VL> VVL;
typedef pair<int, int> PII;

#define FOR(i, a, n) for (ll i = (ll)a; i < (ll)n; ++i)
#define REP(i, n) FOR(i, 0, n)
#define ALL(x) x.begin(), x.end()
#define MOD 1000000007
#define INF (1LL << 25) // 33554432
#define PI 3.14159265359
#define EPS 1e-12
//#define int ll

int t[90000];
signed main(void) {
  while (true) {
    int n;
    string s[10010], f[10010];
    cin >> n;
    if (n == 0)
      break;
    REP(i, 86401) t[i] = 0;
    REP(i, n) {
      cin >> s[i] >> f[i];
      int sh = stoi(s[i].substr(0, 2)), sm = stoi(s[i].substr(3, 2)),
          ss = stoi(s[i].substr(6, 2)), fh = stoi(f[i].substr(0, 2)),
          fm = stoi(f[i].substr(3, 2)), fs = stoi(f[i].substr(6, 2));
      t[sh * 60 * 60 + sm * 60 + ss]++;
      t[fh * 60 * 60 + fm * 60 + fs]--;
      // cout << sh*60*60+sm*60+ss << " " << fh*60*60+fm*60+fs << endl;
    }

    FOR(i, 1, 86401) { t[i] += t[i - 1]; }

    int ret = 0;
    REP(i, 86401) { ret = max(ret, t[i]); }
    cout << ret << endl;
  }

  return 0;
}

C++: #include <iostream>
#include <algorithm>
#include <vector>
using namespace std;
typedef  pair<int,int>P;
int main(){
  int n;
  vector<P>ve;
  while(cin >> n,n){
    int T[10000] = {0},S[10000] = {0};
    for(int i = 0 ; i < n ; i++ ){
      int a,b,c;
      char ch;
      cin >> a >> ch >> b >> ch >> c;
      S[i] = a*3600 + b*60 + c;
      cin >> a >> ch >> b >> ch >> c;
      T[i] = a*3600 + b*60 + c;
      ve.push_back(P(T[i],S[i]));
    }

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

    int ans = 1,p = 0;
    for(int i = 0 ; i < n-1 ; i++ ){
      if(ve[i].first > ve[i+1].second ){ans++;}
      if(ve[p].first <= ve[i].second && ans > 1 ){ans--;p++;}
    }
    cout << ans << endl;
  }
}

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

int sec(int h,int m,int s){
	return (h*60+m)*60+s;
}
int main(){
	int n;
	while(cin>>n,n){
		map<int,int> mp;
		map<int,int>::iterator it;
		int ans=0;
		for(int i=0;i<n;i++){
			int h,m,s;
			scanf("%d:%d:%d",&h,&m,&s);
			++mp[sec(h,m,s)];
			scanf("%d:%d:%d",&h,&m,&s);
			--mp[sec(h,m,s)];
		}
		int use=0;
		for(it=mp.begin();it!=mp.end();++it){
			use += it->second;
			ans = max(ans,use);
		}
		cout<<ans<<endl;
	}
	return 0;
}

C++: #include <iostream>
#include <algorithm>
#include <vector>
#define rep(i,n) for(int i = 0; i < ((int)(n)); i++)

using namespace std;
typedef vector<int> vi;

int n, t;
string s;
vi TIME;
vi csum;
/*FUNCs=================================================*/
void solve() {

    TIME.assign(24*3600, 0);
    csum.assign(24*3600+1, 0);
    rep(i,n) {
        cin >> s;
        t = stoi(s.substr(0, 2))*3600 + stoi(s.substr(3, 2))*60 + stoi(s.substr(6,2));
        TIME[t] += 1;
        cin >> s;
        t = stoi(s.substr(0, 2))*3600 + stoi(s.substr(3, 2))*60 + stoi(s.substr(6,2));
        TIME[t] -= 1;
    }
    rep(i, 24*3600) csum[i+1] += csum[i] + TIME[i];
    sort(csum.rbegin(), csum.rend());
    cout << csum[0] << '\n';
}

/*MAIN==================================================*/
signed main(){

    while(cin >> n && n!=0) {
        solve();
    }

    return 0;
}

C++: #include <iostream>
#include <algorithm>
#include <cmath>

using namespace std;

int main(){
  while(1){
  int n;
  cin >> n;
  if(n==0)break;

  int hs,ms,ss,he,me,se,S[10000],E[10000];

   for(int i=0; i < n; i++){
     scanf("%d:%d:%d",&hs,&ms,&ss);
     scanf("%d:%d:%d",&he,&me,&se);  
     S[i]=hs*10000+ms*100+ss;
     E[i]=he*10000+me*100+se;
   }
   int cnt=0,Max=0;
   for(int i=0; i < n-1 ;i++){
   for(int j=i+1; j < n ;j++){

     if(E[i] > S[j])cnt++;
     else break;
   }
   Max = max(Max,cnt);
   cnt = 0;
   }
   cout << Max+1 << endl;
   }
  return 0;
}