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>

#define rep(i, n) for (int i=0;i<n;i++)
using namespace std;

int main() {
    while (true) {
        vector<int> imos(24 * 60 * 60+1, 0);
        int n;
        cin>>n;
        if (n==0)
            break;
        rep(i,n){
            int h,m,s;
            char c;
            cin>>h>>c>>m>>c>>s;
            imos[h*60*60+m*60+s]++;
            cin>>h>>c>>m>>c>>s;
            imos[h*60*60+m*60+s]--;
        }

        rep(i,24*60*60){
            imos[i+1]+=imos[i];
        }
        int ans=-1;
        rep(i,24*60*60){
            ans=max(ans,imos[i]);
        }
        cout<<ans<<endl;

    }
    return 0;


}

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

struct TIME {
	int time;
	int start;
	bool operator<(const TIME &t){
		if( time == t.time ){
			return start<t.start;
		}
		return time<t.time;
	}
};

int main() {
	while(true){
		
		vector<TIME> times;
		
		int n;
		cin >> n;
		if(n==0)break;
		
		for(int i=0;i<n;i++){
			int h,m,s;
			char c;
			cin >> h >> c >> m >> c >> s;
//			cout << h <<":"<<m<<":"<<s <<endl; 
			TIME t0={h*60*60+m*60+s,1};
			times.push_back(t0);

			cin >> h >> c >> m >> c >> s;
//			cout << h <<":"<<m<<":"<<s<<endl; 
			TIME t1={h*60*60+m*60+s,0};
			times.push_back(t1);
		}

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

		int count=0;
		int ans=0;
		for(TIME &t : times){
//			cout << t.start << " " << t.time << endl;;
			if(t.start==1){
				count++;
				ans=max(count,ans);
			}else{
				count--;
			}
		}
		cout << ans << endl;
	}
	
	
	return 0;
}

C++: #include<iostream>
#include<vector>
#include<string>
#include<algorithm>
#include<map>
#define int long long
using namespace std;

signed main() {
	int a;
	while (cin >> a,a) {
		multimap<int, int>s;
		for (int b = 0; b < a; b++) {
			string c;
			cin >> c;
			int e =(c[0]-48) * 36000 + (c[1] - 48) * 3600 + (c[3] - 48) * 600 + (c[4] - 48) * 60 + (c[6] - 48)*10+ (c[7] - 48);
			s.insert(pair<int, int>(e, 1));
			cin >> c;
			e = (c[0] - 48) * 36000 + (c[1] - 48) * 3600 + (c[3] - 48) * 600 + (c[4] - 48) * 60 + (c[6] - 48)*10 + (c[7] - 48);
			s.insert(pair<int, int>(e, -1));
		}
		int p = 0, q = 0;
		for (auto g = s.begin(); g != s.end(); g++) {
			q += (*g).second;
			p = max(p, q);
		}
		cout << p << endl;
	}
}

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

const int TIME = 60 * 60 * 24 + 60;
int data[TIME];

int main(){
	cin.tie(0);
	ios::sync_with_stdio(false);
	
	int n;
	while(cin >> n && n){
		for(int i = 0; i < 100; ++i){
			data[i] = 0;
		}
		
		int a, b, c;
		for(int i = 0; i < n; ++i){
			scanf("%d:%d:%d", &a, &b, &c);
			data[a * 60 * 60 + b * 60 + c] ++;
			
			scanf("%d:%d:%d", &a, &b, &c);
			data[a * 60 * 60 + b * 60 + c] --;
		}
	
		int ans = 0;
		for(int i = 0; i < 100; ++i){
			if(i > 0)
				data[i] += data[i - 1];
			ans = max(ans, data[i]);
		}
		
		cout << ans << endl;
	}
	return 0;
}

C++: #include <iostream>
#include <string>
#include <stdlib.h>
#define llint long long

using namespace std;

llint n;
llint diff[100005];
string s, t;

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

int main(void)
{
  while(1){
    cin >> n;
    if(n == 0) break;
    for(int i = 0; i < 100005; i++) diff[i] = 0;
    for(int i = 1; i <= n; i++){
      cin >> s >> t;
      diff[calc(s)]++, diff[calc(t)]--;
    }
    llint ans = diff[0];
    for(int i = 1; i < 100005; i++){
      diff[i] += diff[i-1];
      ans = max(ans, diff[i]);
    }
    cout << ans << endl;
  }
  return 0;
}

C++: #include <bits/stdc++.h>
using namespace std ;

#define pb(n) push_back(n)
#define fi first
#define se second
#define all(r) begin(r),end(r)
#define vmax(ary) *max_element(all(ary))
#define vmin(ary) *min_element(all(ary))
#define debug(x) cout<<#x<<": "<<x<<endl
#define fcout(n) cout<<fixed<<setprecision((n))
#define scout(n) cout<<setw(n)
#define vary(type,name,size,init) vector< type> name(size,init)
#define vvl(v,w,h,init) vector<vector<ll>> v(w,vector<ll>(h,init))
#define mp(a,b) make_pair(a,b)

#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 repi(it,array) for(auto it = array.begin(),end = array.end(); it != end;++it)
#define repa(n,array) for(auto &n :(array))

using ll = long long;
using pii = pair<int,int> ;
using pll = pair<ll,ll> ;

template<typename T>
void O(T t){
  cout << t << endl;
}

const ll mod = 1e9+7;
constexpr ll inf = ((1<<30)-1)*2+1 ;
constexpr double PI = acos(-1.0) ;
double eps = 1e-10 ;
const int dy[] = {-1,0,1,0,1,-1,1,-1};
const int dx[] = {0,-1,0,1,1,-1,-1,1};

inline bool value(int x,int y,int w,int h){
  return (x >= 0 && x < w && y >= 0 && y < h);
}

int main(){
  cin.tie(0);
  ios::sync_with_stdio(false);
  ll n;
  while(cin >> n,n){
    vector<pair<string,string>> s(n);
    rep(i,n){
      cin >> s[i].fi >> s[i].se;
    }
    int c = 1;
    sort(all(s));
    vector<string> t;
    t.push_back(s[0].se);
    rep(i,n-1){
      bool f = false;
      rep(j,t.size()){
        if(s[i+1].fi >= t[j]){
          f = true;
          t[j] = s[i+1].se;
          break;
        }
      }
      if(!f){
        ++c;
        t.push_back(s[i+1].se);
      }
    }
    std::cout << c << std::endl;
  }
  return 0;
}