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 <algorithm>
#include <cstdio>
#include <cstdlib>
#include <vector>
#include <iostream>
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 * 60 * 60 + m * 60 + s];
			scanf("%d:%d:%d", &h, &m, &s);
			--cnt[h * 60 * 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++: #define _CRT_SECURE_NO_WARNINGS // #pragma warning(disable:4996)
#include <iostream>
#include <cstdio>
#include <cstring>
#include <algorithm>
#include <vector>
#include <string>
#include <queue>
#include <functional>
#include <sstream>
#include <cmath>
#include <set>
#include <map>
#include <stack>
using namespace std; 

#define rep(i,a,b) for(int i=(a);i<(b);i++)
#define rrep(i,a,b) for(int i=(a);i>=(b);i--)
#define pb push_back
#define mp(a,b) make_pair(a,b)
#define all(a) a.begin(),a.end()
#define len(x) ((int)(x).size())
#define tmax(a,b,c) max((a),max((b),(c)))
#define tmin(a,b,c) min((a),min((b),(c)))
#define debug(x) cerr << #x << " is " << x << endl;
#define debug2(x,y) cerr << #x << " is " << x << " " << #y << " is " << y << endl;
#define debuga(g,h,w) rep(i,0,h) { rep(j,0,w) cout << g[i][j] << " "; cout << endl;}
#define debugv(v) for(auto&& x : v){cout << x << " ";} cout << endl;

typedef pair<int, int> Pii;
typedef map<int, int> Mii;
typedef vector<int> Vi;
typedef vector<vector<int> > VVi;
typedef long long ll;
const int inf = 2e9;
const ll ll_inf = 1e17;
const int mod = 1e9 + 7;
const long double eps = 1e-10;
typedef pair<ll, ll> Pll; 

int g[101010];

int calc(int h, int m, int s) 
{
	return h*60*60 + m*60 + s;
}

int main()
{
	int n;
	while (cin >> n && n != 0) {
		memset(g,0,sizeof(g));
		rep(i,0,n) {
			Vi a(3);
			char b, c;
			rep(j,0,3) {
				cin >> b >> c;
				b=='0' ? a[j] = (int)(c-'0') : a[j] = (int)(b-'0')*10 + (int)(c-'0');
				if (j != 2) cin >> b;
			}
			g[calc(a[0], a[1], a[2])]++;
			rep(j,0,3) {
				cin >> b >> c;
				b=='0' ? a[j] = (int)(c-'0') : a[j] = (int)(b-'0')*10 + (int)(c-'0');
				if (j != 2) cin >> b;
			}
			g[calc(a[0], a[1], a[2])]--;
		}
		int ans = 0;
		rep(i,1,101010) {
			g[i] = g[i] + g[i-1];
			ans = max(ans, g[i]);
		}
		cout << ans << endl;
	}

	return 0;
}

C++: #include <bits/stdc++.h>
using namespace std;
struct Fast {Fast(){std::cin.tie(0);ios::sync_with_stdio(false);cout.precision(20);}} fast;

/* define */
#define FOR(I,X,Y) for(long long (I)=(X);(I)<(Y);(I)++)
#define REP(I,X,Y) for(long long (I)=(Y)-1;(I)>=(X);(I)--)
#define ALL(X) (X).begin(),(X).end()
#define pb push_back
#define COUNT(V,X) (upper_bound((V).begin(),(V).end(),X)-lower_bound((V).begin(),(V).end(),X))
#define debug(x) cerr<<#x<<':'<<x<<endl;
#define DEBUG(v) cerr<<#v<<':';for(auto xXx:v)cerr<<xXx<<' ';cerr<<endl;
#define Yes(X) if(X){cout<<"Yes"<<endl;}else{cout<<"No"<<endl;}
#define YES(X) if(X){cout<<"YES"<<endl;}else{cout<<"NO"<<endl;}
#define ctoi(C) (C-'0')
#define pow2(x) ((long long)((long long)1<<x))

/* alias */
using ll = long long;
using ld = long double;
using vi = vector<int>;
using vii = vector<vector<int>>;
using vl = vector<long long>;
using vll = vector<vector<long long>>;
using pi = pair<int,int>;
using pl = pair<long long,long long>;
template<typename T> using PQ = priority_queue<T>;
template<typename T> using minPQ = priority_queue<T, vector<T>, greater<T>>;

/* const */
const long long dx[] = {1,0,-1,0};
const long long dy[] = {0,1,0,-1};
const long long dx8[] = {1,1,0,-1,-1,-1,0,1};
const long long dy8[] = {0,1,1,1,0,-1,-1,-1};
const long long dx9[] = {1,1,0,-1,-1,-1,0,1,0};
const long long dy9[] = {0,1,1,1,0,-1,-1,-1,0};
const int INF = 1000000007;
const long long LINF = 1000000000000000007;

/* func */
template <typename T> inline bool chmin(T& a, const T& b) {if (a > b) a = b; return a > b;}
template <typename T> inline bool chmax(T& a, const T& b) {if (a < b) a = b; return a < b;}
long long max(long long x,int y){return max(x,(long long)y);}
long long max(int x,long long y){return max((long long)x,y);}
long long min(long long x,int y){return min(x,(long long)y);}
long long min(int x,long long y){return min((long long)x,y);}

/* liblary */



/* main */

ll t(string s){
    ll hh = stoi(s.substr(0,2));
    ll mm = stoi(s.substr(3,2));
    ll ss = stoi(s.substr(6,2));
    return hh*3600 + mm*60 + ss;
}

int imos[100000];
void solve(int n){
    FOR(i,0,100000)imos[i] = 0;
    FOR(i,0,n){
        string s1,s2;
        cin >> s1 >> s2;
        ll S,T;
        S = t(s1);
        T = t(s2);
        imos[S] += 1;
        imos[T] -= 1;
    }
    FOR(i,1,100000)imos[i] += imos[i-1];
    cout << *max_element(imos,imos+100000) << endl;
}

signed main(){
    int n;
    while(cin >> n){
        if(n == 0)break;
        solve(n);
    }
}