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 <algorithm>
#include <string>
#include <vector>
#include <cstdio>
#include <cmath>
#include <cstdlib>
#include <cstring>
#include <stack>
#include <queue>
#include <set>
#include <map>
#include <unordered_map>
#include <ctime>
#include <list>
#include <numeric>
#include <utility>
#include <ctime>
#define INF 1000000000
#define LINF 9000000000000000000
#define mod 1000000007
 
#define rep(i,n) for(int i=0;i<int(n);i++)
#define REP(i,a,b) for(int i=(a);i<int(b);i++)
#define all(x) (x).begin(),x.end()
#define pb push_back
#define mp make_pair
#define MOD(x) (x%(mod))
 
using namespace std;
 
typedef long long ll;
typedef unsigned long long ull;
typedef vector<int> vi;
typedef pair<int,int> pi;
 
int dx[4]={1,0,-1,0};
int dy[4]={0,1,0,-1};
bool debug=false;
 
/*---------------------------------------------------*/

void solve(int n){
  int h,m,s;
  int imos[86405]={0};
  rep(i,n){
    scanf("%d:%d:%d",&h,&m,&s);
    imos[h*3600+m*60+s]++;
    scanf("%d:%d:%d",&h,&m,&s);
    imos[h*3600+m*60+s]--;
  }
  REP(i,1,86405)imos[i]+=imos[i-1];
  int ans=0;
  rep(i,86405){
    ans=max(ans,imos[i]);
  }
  cout<<ans<<endl;
}

int main(){
  int n;
  while(scanf("%d",&n),n){
    solve(n);
  }
  return 0;
}

C++: #include <cstdlib>
#include <iostream>
#include <string>
#include <vector>
#include <sstream>
#include <algorithm>
using namespace std;
string IntToString(int);
int StringToInt(string);

vector<string> split(string str,string delim){
  vector<string> items;
  size_t dlm_idx;
  if(str.npos == (dlm_idx = str.find_first_of(delim))){
    items.push_back(str.substr(0,dlm_idx));
  }
  while(str.npos != (dlm_idx = str.find_first_of(delim))){
    if(str.npos == str.find_first_not_of(delim)){
      break;
    }
    items.push_back(str.substr(0,dlm_idx));
    dlm_idx++;
    str = str.erase(0,dlm_idx);
    if(str.npos == str.find_first_of(delim) && "" != str){
      items.push_back(str);
      break;
    }
  }
  return items;
}
void fill(vector<int> &a,int s,int l){
  for(int i = s;i < l;i++){
    a[i]++;
  }
}
int make_time(vector<string> &a){
  int time = 0;
  time = StringToInt(a[0])*60*60+StringToInt(a[1])*60+StringToInt(a[2]);
  return time;
}
int main(){
  while(1){
    int n;
    cin >> n;
    if(n == 0)break;
    vector<int> zone(60*60*24+1,0);
    for(int i = 0;i < n;i++){
      string tmp;
      cin >> tmp;
      vector<string> from = split(tmp,":");
      cin >> tmp;
      vector<string> to = split(tmp,":");
      fill(zone,make_time(from),make_time(to));
    }
    int ans = 0;
    for(int i = 0;i < 60*60*24+1;i++){
      ans = max(zone[i],ans);
    }
    cout << ans << endl;
      
    
  }
  return 0;
}
string IntToString(int number){
  stringstream ss;
  ss << number;
  return ss.str();
}
int StringToInt(string number){
  stringstream ss;
  ss << number;
  int numInt;
  ss >> numInt;
  return numInt;
  
}