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

#define REP(i,n) for(int i=0; i<n; i++)
#define debug(x) cerr << __LINE__ << " : " << #x << " = " << (x) << endl;
 
#define mod 1000000007 //1e9+7(prime number)
#define INF 1000000000 //1e9
#define SIZE 86400	// 60*60*24

using namespace std;
typedef long long ll;

int main(){
	while(1){
		int n, data[SIZE], h, m, s, t, ans;
		
		cin >> n;
		if (n==0) break;
		REP(i,SIZE) data[i] = 0;
		ans = 0;
		
		REP(i,n){
			scanf("%d:%d:%d", &h, &m, &s);
			t = h*60*60 + m*60 + s;
			data[t]++;
			scanf("%d:%d:%d", &h, &m, &t);
			t = h*60*60 + m*60 + s;
			data[t]--;
		}
		
		for (int i=1; i<SIZE; i++) data[i]+=data[i-1];
		
		REP(i,SIZE) if (ans<data[i]) ans = data[i];
		
		cout << ans << endl;
	}
	return 0;
}

C++: #include<iostream>
#include<iomanip>
#include<cmath>
#include<string>
#include<vector>
#include<list>
#include<algorithm>
#include<map>
#include<set>
#include<queue>
#include<stack>
using namespace std;
typedef long long ll;
#define fi first
#define se second
#define mp make_pair
const int inf=1e9+7;
const ll mod=1e9+7;
const ll big=1e18;

int DP[100000];

int main() {
    int N;
    vector<int> ansarr;
    string s, t;
    int sh, sm, ss, th, tm, ts;
    int ans;
    while(true){
        for(int i=0;i<100000;++i){
            DP[i] = 0;
        }
        cin>>N;
        if(N==0) break;
        for(int i=0;i<N;++i){
            cin>>s>>t;
            sh = stoi(s.substr(0, 2));
            sm = stoi(s.substr(3, 2));
            ss = stoi(s.substr(6, 2));
            th = stoi(t.substr(0, 2));
            tm = stoi(t.substr(3, 2));
            ts = stoi(t.substr(6, 2));
            DP[sh*60*60+sm*60+ss]++;
            DP[th*60*60+tm*60+ts]--;
        }
        for(int i=1;i<100000;++i){
            DP[i] += DP[i-1];
        }
        ans = 0;
        for(int i=0;i<100000;++i){
            if(ans<DP[i]) ans = DP[i];
        }
        ansarr.push_back(ans);
    }
    for(int i=0;i<ansarr.size();++i){
        cout<<ansarr[i]<<endl;
    }
}

C++: #include <cstdio>
#include <cmath>
#include <cstring>
#include <cstdlib>
#include <climits>
#include <ctime>
#include <queue>
#include <stack>
#include <algorithm>
#include <list>
#include <vector>
#include <set>
#include <map>
#include <iostream>
#include <deque>
#include <complex>
#include <string>
#include <iomanip>
#include <sstream>
#include <bitset>
#include <valarray>
#include <iterator>
using namespace std;
typedef long long int ll;
typedef unsigned int uint;
typedef unsigned char uchar;
typedef unsigned long long ull;
typedef pair<int, int> pii;
typedef vector<int> vi;

#define REP(i,x) for(int i=0;i<(int)(x);i++)
#define FOR(i,c) for(__typeof((c).begin())i=(c).begin();i!=(c).end();i++)
#define RREP(i,x) for(int i=((int)(x)-1);i>=0;i--)
#define RFOR(i,c) for(__typeof((c).rbegin())i=(c).rbegin();i!=(c).rend();i++)
#define ALL(container) container.begin(), container.end()
#define RALL(container) container.rbegin(), container.rend()
#define SZ(container) ((int)container.size())
#define mp(a,b) make_pair(a, b)
#define UNIQUE(v) v.erase( unique(v.begin(), v.end()), v.end() );

template<class T> bool chmax(T &a, const T &b) { if (a<b) { a=b; return 1; } return 0; }
template<class T> bool chmin(T &a, const T &b) { if (a>b) { a=b; return 1; } return 0; }
template<class T> ostream& operator<<(ostream &os, const vector<T> &t) {
os<<"["; FOR(it,t) {if(it!=t.begin()) os<<","; os<<*it;} os<<"]"; return os;
}
template<class T> ostream& operator<<(ostream &os, const set<T> &t) {
os<<"{"; FOR(it,t) {if(it!=t.begin()) os<<","; os<<*it;} os<<"}"; return os;
}
template<class S, class T> ostream& operator<<(ostream &os, const pair<S,T> &t) { return os<<"("<<t.first<<","<<t.second<<")";}

const int INF = 1<<28;
const double EPS = 1e-8;
const int MOD = 1000000007;


int n;

main(){
	while(scanf("%d", &n), n){
		vector<int> idx(86402);
		REP(i, n){
			int h,m,s;
			scanf("%d:%d:%d", &h, &m, &s);
			idx[h*3600+m*60+s+1] ++;
			scanf("%d:%d:%d", &h, &m, &s);
			idx[h*3600+m*60+s+1] --;
		}
		int ans = 0;
		REP(i, 86401){
			chmax(ans, idx[i+1] += idx[i]);
		}
		cout << ans << endl;
	}
	return 0;
}