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 <vector>
#include <algorith>
using namespace std;

int solve(int n){
  vector< pair<int,int> > tm;
  char ch1,ch2;
  int h,m,s;
  for(int i=0;i<n;i++){
    cin>>h>>ch1>>m>>ch2>>s;
    tm.push_back(make_pair(h*3600+m*60+s,1));
    cin>>h>>ch1>>m>>ch2>>s;
    tm.push_back(make_pair(h*3600+m*60+s,-1));
  }
  sort(tm.begin(),tm.end());
  int res=0;
  int co=0;
  for(int i=0;i<(int)tm.size();i++){
    co+=tm[i].second;
    res = max(co,res);
  }
  return res;
}
    
  

int main (){
  int n;
  while(cin>>n && n){
      cout<<solve(n)<<endl;
  }
  return 0;
}

C++: #include<bits/stdc++.h>
#define rep(i,n) for(int i=0; i<n; i++)
using namespace std;
int main(){
  int n;
  int Max = 24*3600+59*60+59;
  while(cin >> n,n){
    vector<int> v(Max+1,0);
    string s1,s2;
    rep(i,n){
     cin >> s1 >> s2;
     int sum1=0,sum2=0;
     for(int j=0; j<s1.size(); j+=3){
      if(j==0){
        sum1 += atoi(s1.substr(j,2).c_str())*3600;
        sum2 += atoi(s2.substr(j,2).c_str())*3600;
      }
      if(j==3){
        sum1 += atoi(s1.substr(j,2).c_str())*60;
        sum2 += atoi(s2.substr(j,2).c_str())*60;
      }
      if(j==6){
        sum1 += atoi(s1.substr(j,2).c_str());
        sum2 += atoi(s2.substr(j,2).c_str());
      }
     }
     v[sum1]++; v[sum2]--;
    }
    int ans = 0;
    rep(i,Max){
      v[i+1] += v[i];
      ans = max(ans,v[i+1]);
    }
    cout << ans << 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){
    ve.clear();
    int t,s;
    for(int i = 0 ; i < n ; i++ ){
      int a,b,c;
      char ch;
      cin >> a >> ch >> b >> ch >> c;
      s = a*3600 + b*60 + c;
      cin >> a >> ch >> b >> ch >> c;
      t = a*3600 + b*60 + c;
      ve.push_back(P(t,s));
    }

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

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

      cout << "----b--------" << endl;
      cout << ve[p].first << endl;
      cout << ans << endl;
      cout << "-------------" << endl; 
      cout << "-------------" << endl << endl;*/
    }
    cout << ans << endl;
  }
  return 0;
}

C++: #include<iostream>
#include<algorithm>
#include<string>
#include<cmath>
using namespace std;

int Time(string t, string h, string m, string s){
  h = t.substr(0, 2);
  m = t.substr(3, 2);
  s = t.substr(6, 2);
  return atoi(h.c_str())*3600 + atoi(m.c_str())*60 + atoi(s.c_str());
}

int main(int argc, char *argv[]){
  int n;
  while(cin >> n, n){
    int table[24*3600] = {0};
    string t;
    for (int i = 0; i < n; i++) {
      cin >> t;
      string h, m, s;
      int st = Time(t, h, m, s);
      cin >> t;
      int e  = Time(t, h, m, s);
      table[st]++;
      table[e]--;
    }
    int a = 0;
    int Max = 0;
    for (int i = 0; i < 24*3600; i++) {
      a += table[i];
      Max = max(Max, a);
    }
    std::cout << Max << std::endl;
  }
  return 0;
}

C++: #include <iostream>
#include <string>
#include <map>
#include <vector>
#include <utility>
#include <set>
#include <stack>
#include <queue>
#include <deque>
#include <algorithm>

#define rep(i,j,k) for(int i=(int)j;i<(int)k;i++)
#define itrep(i,x) for(auto i=(x).begin(); i!=(x).end();i++)
#define Sort(x) sort((x).begin(),(x).end())
#define all(x) (x).begin(),(x).end()
#define fi first
#define se second
#define vec vector
#define INF INT_MAX
#define INFL 1e18
#define MOD 1000000007
#define pb push_back
#define MP make_pair
#define PI 3.1415926535
typedef long long int ll;
typedef std::pair<int,int> P;
int D=1;
int dx[4]={0,1,0,-1},dy[4]={-1,0,1,0};
const int limit=60;
using namespace std;

int main(){
    int n;
    int t=24*3600+59*60+59;
    while(cin>>n&&n){
        vector<int> v(t+1,0);
        rep(i,0,n){
            int hs,ms,ss,he,me,se;
            scanf("%d:%d:%d",&hs,&ms,&ss);
            scanf("%d:%d:%d",&he,&me,&se);
            v[hs*3600+ms*60+ss]++;
            v[he*3600+me*60+se]--;
        }

        int ans=0;
        rep(i,0,t){
            v[i+1]+=v[i];
            /*if(ans<v[i+1]){
                int ii=i;
                cout<<i/3600<<" "<<(i%3600)/60<<" "<<(i%60)<<endl;
            }*/
            ans=max(ans,v[i+1]);
        }
        cout<<ans<<endl;

    }
    
    return 0;
}

/*
111000
011000
001000
000100
000110
000111
*/

C++: #include<iostream>
#include<string>
#include<vector>
#include<map>
#include<algorithm>
using namespace std;
typedef pair<int,int> se;
typedef vector<se> tt;
int main(){
  int n;
  cin>> n;
  while(n!=0){
    int i,j,k;
    string str;
    tt t;
    for(i=0;i<n;i++){
      int st=0,et=0;
      cin >> str;
      st+=((str[0]-'0')*10+str[1]-'0')*24*60;
      st+=((str[3]-'0')*10+str[4]-'0')*60;
      st+=((str[6]-'0')*10+str[7]-'0');
      cin >> str;
      et+=((str[0]-'0')*10+str[1]-'0')*24*60;
      et+=((str[3]-'0')*10+str[4]-'0')*60;
      et+=((str[6]-'0')*10+str[7]-'0');
      t.push_back(make_pair(st,et));
    }
    sort(t.begin(),t.end());
    int m=0,b;
    for(j=0;j<86401;j++) {
      b=0;
      for(k=0;k<t.size();k++){
	if(t[k].first<=j&&j<t[k].second) b++;
	if(t[k].first>j) break;
      }
      if(m<b) m=b;
    }
    cout << m << endl;
    cin >> n;
  }
  return 0;
}