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 <cstdlib>
#include <cstring>
#include <cmath>
#include <ctime>
#include <cctype>
#include <climits>
#include <iostream>
#include <string>
#include <vector>
#include <map>
#include <list>
#include <queue>
#include <deque>
#include <algorithm>
#include <numeric>
#include <utility>
#include <complex>
#include <memory>
#include <functional>
#include <set>

using namespace std;

#define ALL(g) (g).begin(),(g).end()
#define REP(i, x, n) for(int i = x; i < (int)(n); i++)
#define rep(i,n) REP(i,0,n)
#define F(i,j,k) fill(i[0],i[0]+j*j,k)
#define P(p) cout<<(p)<<endl;
#define EXIST(s,e) ((s).find(e)!=(s).end())
#define INF 1<<25
#define pb push_back
typedef vector<int> vi;
typedef vector<long long> vl;
typedef vector<double> vd;
typedef pair<int, int> pii;
typedef pair<long, long> pll;
typedef long long ll;

int main()
{
    while(1){
    
        vector<int>startH;
        vector<int>startM;
        vector<int>startS;
        vector<int>goalH;
        vector<int>goalM;
        vector<int>goalS;
        int n;
        int ans = 1;
        bool flag=false;
        int mh,mm,ms,mh2,mm2,ms2;
        cin >> n;
        
        if(n == 0)return 0;
        
        for(int i=0;i<n;i++){
            scanf("%d:%d:%d %d:%d:%d",&mh,&mm,&ms,&mh2,&mm2,&ms2);
            startH.push_back(mh*10000);
            startM.push_back(mm*100);
            startS.push_back(ms);
        
            goalH.push_back(mh2*10000);
            goalM.push_back(mm2*100);
            goalS.push_back(ms2);
        }
         int hassya[n],toutyaku[n];
        for(int i=0;i<n;i++){
           
            hassya[i] = startH[i] + startM[i] + startS[i];
            toutyaku[i] = goalH[i] + goalM[i] + goalS[i];
            
        }
        for(int i=1;i<n;i++){
            for(int j=0;j < i; j++ ){
                if(hassya[i] < toutyaku[j]){

                }else{
                    toutyaku[j] = 0;
                    flag=true;
                    break;
                }
            }
            if(!flag){
                ans++;
            }
            
        }
        cout << ans << endl;
        
        ans  = 1;
    }
    return 0;
}

C++: #include <bits/stdc++.h>
using namespace std;
#define rep(i, n) for (int i = 0; i < (int)(n); i++)
#define rrep(i, n) for (int i = (int)(n - 1); i >= 0; i--)
#define all(x) (x).begin(), (x).end()
#define sz(x) int(x.size())
#define get_unique(x) x.erase(unique(all(x)), x.end());
typedef long long ll;
typedef complex<double> Complex;
const int INF = 1e9;
const ll MOD = 1e9 + 7;
const ll LINF = 1e18;
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 (b < a) {
        a = b;
        return 1;
    }
    return 0;
}
template <class T>
vector<T> make_vec(size_t a) {
    return vector<T>(a);
}
template <class T, class... Ts>
auto make_vec(size_t a, Ts... ts) {
    return vector<decltype(make_vec<T>(ts...))>(a, make_vec<T>(ts...));
}
int f(string s) {
    string hh, mm, ss;
    hh = s.substr(0, 2);
    mm = s.substr(3, 2);
    ss = s.substr(6, 2);
    return 3600 * stoi(hh) + 60 * stoi(mm) + stoi(ss);
}
int main() {
    while (1) {
        int n;
        cin >> n;
        if (!n) return 0;
        vector<int> v(90001);
        rep(i, n) {
            string s, t;
            cin >> s >> t;
            v[f(s)]++;
            v[f(t)]--;
        }
        int ans = 0;
        rep(i, 90000) {
            v[i + 1] += v[i];
            chmax(ans, v[i]);
        }
        cout << ans << endl;
    }
}

C++: #include <iostream>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <cmath>
#include <climits>
#include <vector>
#include <string>
#include <queue>
#include <deque>
#include <list>
#include <stack>
#include <set>
#include <map>
#include <algorithm>

#define MOD7 1000000007
#define MOD9 1000000009

#define rep(i, n) for (int i = 0; i < (n); i++)
#define REP(i, a, n) for (int i = (a); i <= (n); i++)
#define all(a) (a).begin(), (a).end()

using namespace std;

int dx[4] = { 1, 0, -1, 0 };
int dy[4] = { 0, -1, 0, 1 };

int nextInt() {int a; cin >> a; return a;}
char nextChar() {char a; cin >> a; return a;}
double nextDouble() {double a; cin >> a; return a;}
string nextString() {string a; cin >> a; return a;}

void inputVector(vector<int> &v, int &n) {rep(i,n){v.push_back(nextInt());}}
void inputVector(vector<double> &v, int &n) {rep(i,n){v.push_back(nextDouble());}}
void inputVector(vector<string> &v, int &n) {rep(i,n){v.push_back(nextString());}}

int memo[86500];

int timeToInt(string s) {
    int ret = 0;
    ret += (s[0] - '0') * 24000;
    ret += (s[1] - '0') * 2400;
    ret += (s[3] - '0') * 600;
    ret += (s[4] - '0') * 60;
    ret += (s[6] - '0') * 10;
    ret += (s[7] - '0') * 1;
    return ret;
}

signed main() {
    int n;
    while (cin >> n) {
	if (!n) break;

	memset(memo, 0, sizeof(memo));

	rep(i, n) {
	    string s, t;
	    cin >> s >> t;
	    int t1 = timeToInt(s), t2 = timeToInt(t);
	    memo[t1]++;
	    memo[t2]--;
	}
	REP(i, 1, 86400) {
	    memo[i] += memo[i - 1];
	}
	int ret = 0;
	rep(i, 86450) ret = max(ret, memo[i]);
	cout << ret << endl;
    }

    return 0;
}