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 <cstdio>
#include <cctype>
#include <utility>
#include <vector>
#include <algorithm>
using namespace std;

#define gcu getchar_unlocked
#define pcu putchar_unlocked
#define _T template <typename T>
#define _HT template <typename H, typename... T>
#define _il inline
#define _in _il int in
#define _sc _il bool scan
_T T in(int c){T n=0;bool m=false;while(isspace(c)){c=gcu();}if(c=='-')m=true,c=gcu();
	do{n=10*n+(c-'0'),c=gcu();}while(c>='0'&&c<='9');return m?-n:n;}
_in() {return in<int>(gcu());}
_T T scan(T &n){int c=gcu();return c==EOF?false:(n=in<T>(c),true);}
_sc(char &c){c=gcu();gcu();return c!=EOF;}
#ifdef _GLIBCXX_STRING
_sc(string &s){int c;s="";
	for(;;){c=gcu();if(c=='\n'||c==' ')return true;else if(c==EOF)return false;s+=c;}}
#endif
_HT _sc(H &h, T&&... t){return scan(h)&&scan(t...);}
#define _vo _il void out
#define _vl _il void outl
_vo(bool b) {pcu('0'+b);}
_vo(const char *s){while(*s)pcu(*s++);}
_vo(char c){pcu(c);}
#ifdef _GLIBCXX_STRING
_vo(string s){for(char c:s)pcu(c);}
#endif
_T _vo(T n){static char buf[20];char *p=buf;
	if(n<0)pcu('-'),n*=-1;if(!n)*p++='0';else while(n)*p++=n%10+'0',n/=10;
	while (p!=buf)pcu(*--p);}
_vl(){out('\n');}
#ifdef _GLIBCXX_VECTOR
_T _vo(vector<T> &v){for(T &x:v)out(&x == &v[0]?"":" "),out(x);outl();}
#endif
_HT _vo(H&& h, T&&... t){out(h);out(move(t)...);}
template <typename... T> _vl(T&&... t){out(move(t)...);outl();}

int time() {
	int h = in(), m = in();
	return h * 3600 + m * 60 + in();
}

int main() {
	for (int n; (n = in());) {
		vector<pair<int, int>> t;
		while (n--) {
			t.push_back({time(), 1});
			t.push_back({time(), -1});
		}
		sort(t.begin(), t.end());
		int c = 0, m = 0;
		for (auto a: t)
			m = max(c += a.second, m);
		outl(m);
	}
}

C++: #include<iostream>
#include<cstdio>
#include<math.h>
#include<string>
#include<algorithm>
#include<functional>
#include<vector>
#include<set>
#include<map>
#include<queue>
#define INF 999999
#define EPS 1.0e-6

using namespace std;

typedef long long ll;
typedef pair<int, int> P;
typedef pair<int, P> PP;

int main()
{
	int n;
	while (cin >> n) {
		if (n == 0)return 0;
		P a[105000];

		string s1, s2;
		for (int i = 0; i < n; i++) {
			cin >> s1 >> s2;
			int hour1 = (int)(s1[0] - '0') * 10 + (int)(s1[1] - '0');
			int min1= (int)(s1[3] - '0') * 10 + (int)(s1[4] - '0');
			int sec1 = (int)(s1[6] - '0') * 10 + (int)(s1[7] - '0');
			int hour2 = (int)(s2[0] - '0') * 10 + (int)(s2[1] - '0');
			int min2 = (int)(s2[3] - '0') * 10 + (int)(s2[4] - '0');
			int sec2 = (int)(s2[6] - '0') * 10 + (int)(s2[7] - '0');
			a[i].first = 3600 * hour1 + 60 * min1 + sec1;
			a[i].second = 3600 * hour2 + 60 * min2 + sec2;
		}
		sort(a, a + n);
		/*
		for (int i = 0; i < n; i++) {
			cout << a[i].first <<" "<< a[i].second << endl;
		}
		*/

		priority_queue<int,vector<int>,greater<int> >que;
		que.push(a[0].second);
		int cnt = 1;
		for (int i = 1; i < n; i++) {
			
			if (que.empty()) {
				cnt++;
				que.push(a[i].second);
			}
			else {
				int k = que.top();
				if (a[i].first >= k) {
					que.pop();
					que.push(a[i].second);
					continue;
				}
				else {
					cnt++;
					que.push(a[i].second);
				}
			}
		}
		cout << cnt << endl;

	}

	return 0;
}

C++: //include
//------------------------------------------
#include <vector>
#include <list>
#include <map>
#include <set>
#include <queue>
#include <stack>
#include <bitset>
#include <algorithm>
#include <functional>
#include <numeric>
#include <utility>
#include <sstream>
#include <iostream>
#include <iomanip>
#include <cstdio>
#include <cmath>
#include <cstdlib>
#include <cctype>
#include <string>
#include <cstring>
#include <ctime>
#include <fstream>
#include <complex>
#include <math.h>

using namespace std;

//conversion
//------------------------------------------
inline long toInt(string s) {int v; istringstream sin(s);sin>>v;return v;}
inline long toLong(string s) {long v; istringstream sin(s);sin>>v;return v;}
template<class T> inline string toString(T x) {ostringstream sout;sout<<x;return sout.str();}

//math
//-------------------------------------------
template<class T> inline T sqr(T x) {return x*x;}

//typedef
//------------------------------------------
typedef vector<int> VI;
typedef vector<VI> VVI;
typedef vector<string> VS;
typedef pair<int, int> PII;
typedef pair<long, long> PLL;
typedef long long LL;
//container util
//------------------------------------------
#define ALL(a)  (a).begin(),(a).end()
#define RALL(a) (a).rbegin(), (a).rend()
#define PB push_back
#define MP make_pair
#define SZ(a) int((a).size())
#define EACH(i,c) for(typeof((c).begin()) i=(c).begin(); i!=(c).end(); ++i)
#define EXIST(s,e) ((s).find(e)!=(s).end())
#define SORT(c) sort((c).begin(),(c).end())

//repetition
//------------------------------------------
#define FOR(i,a,b) for(long i=(a);i<(b);++i)
#define REP(i,n) FOR(i,0,n)

//constant
//--------------------------------------------

//clear memory
#define CLR(a) memset((a), 0 ,sizeof(a))

const long double EPS = 1e-20;
const long INF = 1e10;

int imos[100000];
int main(){
	int n;
	while(cin>>n){
		if(n==0)break;
		CLR(imos);
		REP(i,n){
			int h,m,s;char c;
			cin>>h>>c>>m>>c>>s;
			imos[h*3600+m*60+s]++;
			cin>>h>>c>>m>>c>>s;
			imos[h*3600+m*60+s]--;
		}
		int res=0,sum=0;
		for(long i=0;i<=100000;i++){
			sum+=imos[i];
			//if(sum>0)cout<<sum<<endl;
			res=max(res,sum);
		}
		cout<<res<<endl;
	}
	return 0;
}