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<string>
#include<sstream>
#include<string.h>
#include<algorithm>

using namespace std;

int timecount[86400];

int stoi(string str){
	stringstream ss;
	int num;
	ss << str;
	ss >> num;
	return num;
}

int hmstot(string str){
	return stoi(str.substr(0,2)) * 3600 + stoi(str.substr(2,2)) * 60 + stoi(str.substr(4,2));
}

int main(){
	while(1){
		memset(timecount, 0,sizeof(timecount));
		int n;
		cin >> n;
		if(n == 0) break;
		
		for(int i = 0;i < n;i++){
			string shms,ghms;
			cin >> shms >> ghms;
			int st,gt;
			st = hmstot(shms);
			gt = hmstot(ghms);
			for(int j = st;j < gt;j++){
				timecount[j]++;
			}
		}
		
		int ans = 0;
		for(int i = 0;i < 86400;i++){
			ans = max(ans,timecount[i]);
		}
		cout << ans << endl;
	}
	return 0;
}

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

int main() {
	const int MAX = 24 * 60 * 60;

	for(int n; scanf("%d", &n), n;) {
		vector<int> cnt(MAX, 0);
		for(int i = 0; i < n; ++i) {
			int h, m, s;
			scanf("%d:%d:%d", &h, &m, &s);
			++cnt[h * 24 * 60 + m * 60 + s];
			scanf("%d:%d:%d", &h, &m, &s);
			--cnt[h * 24 * 60 + m * 60 + s];
		}

		for(int i = 1; i < MAX; ++i)
			cnt[i] += cnt[i - 1];

		printf("%d\n", *max_element(cnt.begin(), cnt.end()));
	}

	return EXIT_SUCCESS;
}

C++: #include<iostream>
#include<cstdio>
#define loop(i,a,b) for(int i=a;i<b;i++)
#define rep(i,a) loop(i,0,a)
#define INF 1e6
using namespace std;

int main(){
	int n,hh[2],mm[2],ss[2];
	while(cin>>n,n){
		int time[86500];
		rep(i,86500)time[i]=0;
		rep(i,n){
			scanf("%d:%d:%d",&hh[0],&mm[0],&ss[0]);
			scanf("%d:%d:%d",&hh[1],&mm[1],&ss[1]);
			time[hh[0]*3600+mm[0]*60+ss[0]]++;
			time[hh[1]*3600+mm[1]*60+ss[1]]--;	
		}
		rep(i,86490){
			time[i+1]+=time[i];
		}
		int inf=0;
		rep(i,86500){
			if(time[i]==0)continue;
			else if(inf<time[i]){
				inf=time[i];
			}
		}
		cout<<inf<<endl;
	}
	return 0;
}

C++: #include <iostream>
#include <vector>
#include <algorithm>
#include <cstdio>
using namespace std;
typedef pair<int,int> P;

int main(){
    int n;
    
    while(cin >> n,n){
        vector<P> v;
        int sh,sm,ss,th,tm,ts,Max=0,Min = 99999,totals,totalt;
        for(int i = 0 ; i < n ; i++){
            scanf("%d:%d:%d" ,&sh , &sm , &ss);
            totals = sh*3600+sm*60+ss;
            v.push_back(P(totals,1));
            scanf("%d:%d:%d" ,&th , &tm , &ts);
            totalt = th*3600+tm*60+ts;
            v.push_back(P(totalt,-1));
        }
        sort(v.begin(),v.end());
    
        int ans = 0,tmp = 0;
        for(int i = 0 ; i < v.size() ; i++){
                tmp += v[i].second;
                ans = max(ans,tmp);
        }
        cout << ans << endl;
    }
    
    return 0;
}

C++: // clang-format off
#include <bits/stdc++.h>
#define int long long
#define main signed main()
// #define main int main()
#define loop(i, a, n) for (int i = (a); i < (n); i++)
#define rep(i, n) loop(i, 0, n)
#define all(v) (v).begin(), (v).end()
#define rall(v) (v).rbegin(), (v).rend()
#define prec(n) fixed << setprecision(n)
#define stlice(from, to) substr(from, (to) - (from) + 1)
#define pb push_back
#define mp make_pair
#define mt make_tuple
#define fi first
#define se second
using namespace std;
typedef pair<int, int> pii;
typedef vector<int> vi;
typedef vector<double> vd;
typedef vector<char> vc;
typedef vector<bool> vb;
typedef vector<string> vs;
typedef vector<pii> vpii;
typedef vector<vi> vvi;
typedef vector<vb> vvb;
typedef vector<vpii> vvpii;
const int INF = sizeof(int) == sizeof(long long) ? 1000000000000000000LL : 1000000000;
const int MOD = 1000000007;
const double PI = acos(-1);
template<typename A, typename B> bool cmin(A &a, const B &b) { return a > b ? (a = b, true) : false; }
template<typename A, typename B> bool cmax(A &a, const B &b) { return a < b ? (a = b, true) : false; }
bool odd(const int &n) { return n & 1; }
bool even(const int &n) { return !odd(n); }
void solve();
main { solve(); return 0; }
// clang-format on

void solve() {
  int n;
  while (cin >> n, n) {
    vi v(86400);
    rep(i, n) {
      int h, m, d;
      char gomi;
      cin >> h >> gomi >> m >> gomi >> d;
      int l = h * 3600 + m * 60 + d;
      cin >> h >> gomi >> m >> gomi >> d;
      int r = h * 3600 + m * 60 + d;
      v[l]++;
      v[r]--;
    }
    loop(i, 1, 86400) v[i] += v[i - 1];
    int c = 0;
    rep(i, 86400) cmax(c, v[i]);
    cout << c << endl;
  }
}