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<bits/stdc++.h>
#include<cstdio>
#include<cstdlib>
#include<iostream>
#include<algorithm>
#include<vector>
#include<stack>
#include<queue>
#include<set>
#include<string>
#include<cmath>
#include<cassert>
#include<map>
#include<sstream>

  using namespace std;

typedef long long ll;
typedef ll int__;
#define rep(i,j) for(int__ (i)=0;(i)<(j);(i)++)
#define repeat(i,j,k) for(int__ i=(j);i<(k);(i)++)
#define all(v) begin(v),end(v)


typedef pair<ll,ll> pii;

bool comp(const pii l,const pii r){
  return l.second==r.second ? l.first<r.first : l.second<r.second;
}

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

    vector<pii> input(n);
    rep(i,n){
      string s,e;cin>>s>>e;
      pii train;
      const char *s_char = s.c_str();
      const char *e_char = e.c_str();
      ll hour,minute,second;
      sscanf(s_char, "%lld:%lld:%lld",&hour,&minute,&second);
      train.second=hour*60*60+minute*60+second;
      sscanf(e_char, "%lld:%lld:%lld",&hour,&minute,&second);
      train.first=hour*60*60+minute*60+second;
      input[i]=train;
    }
    
    sort(all(input),comp);
    
    priority_queue<pii,vector<pii>,greater<pii> > que;
    ll ans=0;
    rep(i,n){
      pii train=input[i];

      while(que.size()>0 && train.second>=que.top().first){
        que.pop();
      }
      que.push(train);
      ans=max(ans,(ll)que.size());
    }
    cout<<ans<<endl;
  }
  
  return 0;
}

C++: #include<iostream>
#include<vector>
#include<string>
using namespace std;
int main(){
	int n,ma;
	string s,t;
	vector<int> box;
	while(cin>>n,n){
		ma=0;
		for(int i=0;i<=24*60*60;i++)
		box.push_back(0);
		for(int i=0;i<n;i++){
			cin>>s>>t;
			for(int j=((s[0]-'0')*10+s[1]-'0')*3600+((s[3]-'0')*10+s[4]-'0')*60+(s[6]-'0')*10+s[7]-'0';j<((t[0]-'0')*10+t[1]-'0')*3600+((t[3]-'0')*10+t[4]-'0')*60+(t[6]-'0')*10+t[7]-'0';j++){
				
				box[j]++;
				if(ma<box[j])
		ma=box[j];
			}
		}
		
		cout<<ma<<endl;
		box.clear();
	}
	return 0;
}

C++: #include <iostream>
#define REP(i,s,n) for(int i=s;i<n;++i)
#define rep(i,n) REP(i,0,n)
#define MAX 10000
using namespace std;
int ans,cou;
int n;
char s[10],g[10];
struct t {
  int h;
  int m;
  int s;
};
t start[MAX],goal[MAX];
int main() {
  while(true){
    cin >> n;
    if(n==0) return 0;
    ans = 0;
    cou = 0;
    rep(i,n){
      cin >> s >> g;
      start[i] = t();
      goal[i] = t();
      start[i].h = (int)(s[0]-'0')*10+(int)(s[1]-'0');
      start[i].m = (int)(s[3]-'0')*10+(int)(s[4]-'0');
      start[i].s = (int)(s[6]-'0')*10+(int)(s[7]-'0');
      goal[i].h = (int)(g[0]-'0')*10+(int)(g[1]-'0');
      goal[i].m = (int)(g[3]-'0')*10+(int)(g[4]-'0');
      goal[i].s = (int)(g[6]-'0')*10+(int)(g[7]-'0');
    }
    rep(i,24) rep(j,60) rep(k,60){
      rep(l,n){
        if(goal[l].h==i&&goal[l].m==j&&goal[l].s==k) cou--;
        if(start[l].h==i&&start[l].m==j&&start[l].s==k) cou++;
      }
      if(cou>ans) ans = cou;
    }
    cout << ans << endl;
  }
  return 0;
}

C++: #include <vector>
#include <iostream>
#include <utility>
#include <algorithm>
#include <string>
#include <deque>
#include <queue>
#include <tuple>
#include <queue>
#include <functional>
#include <cmath>
#include <iomanip>
#include <map>
#include <set>
#include <numeric>
#include <unordered_map>
#include <unordered_set>
#include <complex>
#include <iterator>
#include <array>
#include <memory>
#include <stack>
#define vi vector<int>
#define vvi vector<vector<int> >
#define ll long long int
#define vl vector<ll>
#define vvl vector<vector<ll>>
#define vb vector<bool>
#define vc vector<char>
#define vs vector<string>
#define ld long double
#define INF 1e9
#define EPS 0.0000000001
#define rep(i,n) for(int i=0;i<n;i++)
#define loop(i,s,n) for(int i=s;i<n;i++)
#define all(in) in.begin(), in.end()
template<class T, class S> void cmin(T &a, const S &b) { if (a > b)a = b; }
template<class T, class S> void cmax(T &a, const S &b) { if (a < b)a = b; }
#define MAX 9999999
using namespace std;
typedef pair<int, int> pii;
typedef pair<double,double>pdd;
typedef pair<ll,ll>pll;
typedef pair<int,pii>ppii;
typedef pair<ppii,ppii> d_pii;
ppii cal(string s){
    ppii temp;
    string a,b,c;
    a=s[0]; a+=s[1];
    b=s[3];b+=s[4];
    c=s[6];c+=s[7];
    temp.first=stoi(a);
    temp.second=pii(stoi(b),stoi(c));
    return temp;
}
int main(){
    int n;
    while(cin>>n,n){
        vector<pair<ll,ll>>v;
        rep(i,n){
            string s,e; cin>>s>>e;
            ppii start,end;
            start=cal(s);
            end=cal(e);
            ll _start=start.first*3600+start.second.first*60+start.second.second;
            ll _end=end.first*3600+end.second.first*60+end.second.second;
            v.push_back(make_pair(_start,_end));
        }
        sort(all(v));
        vl u(v.size());
        rep(i,v.size())u[i]=v[i].first;
        ll ans=0;
        ll base=0;
        u.push_back(INF);
        v.push_back(pii(INF,INF));
        rep(i,u.size()){
            ans++;
            base=v[i].second;
            while(true){
                bool update=false;
                vector<ll>::iterator itr=lower_bound(u.begin(), u.end(),base);
                if(itr!=u.end()){
                    int index=(int)(itr-u.begin());
                    update=true;
                    u.erase(itr);
                    base=v[index].second;
                    v.erase(v.begin()+index);
                }
                if(!update)break;
            }
        }
        cout<<ans<<endl;
    }
}