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 <cstdio>
#include <cstdlib>
#include <cmath>
#include <cstring>

#include <iostream>
#include <string>
#include <algorithm>
#include <vector>
#include <queue>
#include <stack>
#include <map>
#include <set>

#include <functional>
#include <cassert>

typedef long long ll;
using namespace std;

#define debug(x) cerr << #x << " = " << x << endl;


#define mod 1000000007 //1e9+7(prime number)
#define INF 1000000000 //1e9
#define LLINF 2000000000000000000LL //2e18
#define SIZE 100010

bool solve(){
  int n;
  int dp[SIZE] = {};
  vector<pair<int,int> > vec;
  
  scanf("%d",&n);

  if(n == 0) return false;


  for(int i=0;i<n;i++){
    int sh,sm,ss,eh,em,es;
    int s,e;

    scanf("%d:%d:%d %d:%d:%d",&sh,&sm,&ss,&eh,&em,&es);

    s = sh*3600 + sm+60 + ss;
    e = eh*3600 + em+60 + es;

    dp[s]++;
    dp[e]--;
    
  }

  int ans = 0;
  
  for(int i=0;i<24*60*60;i++){
    dp[i+1]+= dp[i];
    ans = max(ans, dp[i]);
  }

  printf("%d\n",ans);

  return true;
}


int main(){

  while(solve());
  
  return 0;
}

C++: #include<iostream>
#include<cstdio>
#include<algorithm>
#include<queue>
using namespace std;
#define MAX 10000
#define TOSEC(h,m,s) ((h)*3600+(m)*60+(s))
struct Train{
	int st;
	int ed;
	bool operator<(const Train &t)const{
		return ed < t.ed;
	}
};
int main(){
	while(true){
		Train vt[MAX];
		unsigned int ans = 0;
		int n;
		priority_queue< Train > pq;
		scanf("%d", &n);

		if( n == 0 ) break;

		for(int i = 0; i < n; ++i){
			int sh,sm,ss;
			int eh,em,es;
			Train t;
			
			scanf("%02d:%02d:%02d %02d:%02d:%02d",
				&sh,&sm,&ss,
				&eh,&em,&es);
			t.st = TOSEC(sh,sm,ss);
			t.ed = TOSEC(eh,em,es);

			vt[i] = t;
		}

		sort( vt, vt + n );
		
		for(int i = 0; i < n; ++i){
			if( pq.size() == 0 )
				pq.push( vt[i] );
			else{
				Train tt = pq.top();
				if( tt.ed <= vt[i].st )
					pq.pop();
				else
					pq.push( vt[i] );
			}
			ans = max(ans, pq.size());
		}

		printf("%d\n", ans);
	}
	return 0;
}

C++: #include<iostream>
#include<cstdio>
#include<vector>
#include<algorithm>
 
using namespace std;
 
int dabu(int a, int b,int a1,int b1){
    if (a1>=b)return 0;
    if (b1<=a)return 0;
    return 1;
}

int main(){
    int n;
    vector<vector<int>>jikoku(10000,vector<int>(2));
    while (cin >> n, n){
        int ans=1;
        int ans1 = 1;
        int si,shu;
        for (int i = 0; i < n; i++){
            int  si1, si2, si3, shu1, shu2, shu3;
            scanf("%d:%d:%d %d:%d:%d", &si1, &si2, &si3, &shu1, &shu2, &shu3);
            si = 3600 * si1 + 60 * si2 + si3;
            shu = 3600 * shu1 + 60 * shu2 + shu3;
            jikoku[i][0]=si;
            jikoku[i][1]=shu;
        }
        for(int i=0;i<n;i++){
            ans = 1;
            for (int j=0; j < n; j++){
                if(i==j)continue;
                ans += dabu(jikoku[j][0], jikoku[j][1], jikoku[i][0], jikoku[i][1]);
            }
            ans1 = max(ans, ans1);
        }
        cout << ans1 << endl;
    }
}

C++: #include <bits/stdc++.h>
#define rep(i, n) for (int i = 0; i < (n); i++)
#define shosu(n) setprecision(n)
#define INF 999999999
using namespace std;
int main() {
  int n, t[86400 + 1];
  while (cin >> n, n) {
    memset(t, 0, sizeof(t));
    int H1, H2, M1, M2, S1, S2;
    for (int i = 0; i < n; i++) {
      scanf("%d:%d:%d %d:%d:%d", &H1, &M1, &S1, &H2, &M2, &S2);
      t[H1 * 3600 + M1 * 60 + S1]++;
      t[H2 * 3600 + M2 * 60 + S2]--;
    }
    int ans = 0;
    for (int i = 1; i <= 86400; i++)
      t[i] += t[i - 1];
    cout << *max_element(t, t + 86400) << endl;
  }
  return 0;
}