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 <bits/stdc++.h>
#define PB push_back
#define MP make_pair
#define REP(i,n) for (int i=0;i<(n);i++)
#define FOR(i,a,b) for(int i=(a);i<(b);i++)
#define ALL(a) (a).begin(),(a).end()
#define MOD 100000
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef pair<int,int> P;
const int INF=1e9;
int rec(int h,int m,int s){
      return h*3600+m*60+s;
}
ll cnt[60*60*24+1];
int main(){
      int n;
      while(cin>>n&&n){
            memset(cnt,0,sizeof(cnt));
            int h1,m1,s1,h2,m2,s2;
            REP(i,n){
                  scanf("%d:%d:%d %d:%d:%d",&h1,&m1,&s1,&h2,&m2,&s2);
                  cnt[rec(h1,m1,s1)]++;
                  cnt[rec(h2,m2,s2)+1]--;
            }
            int ans=0;
            REP(i,60*60*24+1){
                  if(i==0)continue;
                  ans=max(cnt[i],ans);
            }
            cout<<ans<<endl;
      }
}

C++: #include <bits/stdc++.h>
using namespace std;

vector<pair<string, int> > v;

int main(){
while(1){//start
	string s, t;
	int n;
	cin >> n;
	if(n == 0) break;

	for(int i = 0; i < n; i++){
		cin >> s >> t;
		v.push_back(make_pair(s, 1));
		v.push_back(make_pair(t, 0));
	}

	sort(v.begin(), v.end());

	int stock = 1;
	int ans = 1;

	for(int i = 0; i < (int)v.size(); i++){
		if(v[i].second){
			if(stock - 1 < 0) ans += 1;
			else stock -= 1;
		}
		else{
			stock += 1;
		}
	}

	cout << ans << endl;

	v.clear();
}//end	

	return 0;
}

C++: #include <iostream>
#include <string>
#include <sstream>
#include <vector>
#include <algorithm>
#define INF 1 << 28
using namespace std;

typedef pair<int,int> P;

int main ()
{
    int n;
    while (cin >> n, n) {
        string str1, str2;
        vector<P> time;
        while (n--) {
            cin >> str1 >> str2;
            for (int i = 0; i < str1.size(); i++) {
                if (str1[i] == ' ') {
                    str1[i] = str2[i] = ' ';
                }
            }

            stringstream ss1, ss2;
            ss1 << str1;
            ss2 << str2;

            int t1, t2, t3;
            ss1 >> t1 >> t2 >> t3;
            int s = t1 * 24 * 60 + t2 * 60 + t3;
            ss2 >> t1 >> t2 >> t3;
            int e = t1 * 24 * 60 + t2 * 60 + t3;

            time.push_back(P(s,e));
        }

        time.push_back(P(INF,INF));
        vector<int> st, et;
        for (int i = 0; i < time.size(); i++) {
            st.push_back(time[i].first);
            et.push_back(time[i].second);
        }

        int k = 0, l = 0;
        int tmp = 0, MAX = 0;
        while (st[k] != INF || et[l] != INF) {
            if (st[k] < et[l]) {
                tmp++;
                k++;
            } else {
                tmp--;
                l++;
            }
            MAX = MAX < tmp ? tmp : MAX;
        }

        cout << MAX << endl;
    }

    return 0;
}

C++: #include <algorithm>
#include <climits>
#include <cmath>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <functional>
#include <iostream>
#include <map>
#include <ostream>
#include <queue>
#include <set>
#include <stack>
#include <string>
#include <vector>
#define INF 1000000000
#define rep(i,a,b) for (int i=(a);i<(b);i++)
#define rev(i,a,b) for (int i=(a)-1;i>=b;i--)
using namespace std;
typedef long long ll;
typedef pair<int, int> pii;
typedef queue<int> qi;
typedef vector<int> vi;
typedef vector<string> vs;
int dx[4] = { 0, 1, 0, -1 };
int dy[4] = { 1, 0, -1, 0 };

int t[90000];

int main() {
	cin.tie(0);
	ios::sync_with_stdio(false);

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

		rep(i,0,90000) t[i] = 0;
		rep(i,0,n) {
			int sH,sM,sS,eH,eM,eS;
			scanf("%d:%d:%d", &sH, &sM, &sS);
			scanf("%d:%d:%d", &eH, &eM, &eS);
			t[sH*3600 + sM*60 + sS]++;
			t[eH*3600 + eM*60 + eS]--;
		}

		int ans = -1, tmp = 0;
		rep(i,0,90000) {
			tmp += t[i];
			ans = max(ans, tmp);
		}
		cout << ans << endl;
	}
	return 0;
}

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(3,2)) * 60 + stoi(str.substr(6,2));
}

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 <bits/stdc++.h>
#define ADAY 86400
using namespace std;

int main(void){
  int n;
  while(cin >> n, n){
    vector < pair < int, int > > t;
    for(int i=0; i < n; i++){
      pair<int, int> tmp;
      int h, m, s;
      scanf("%d:%d:%d", &h, &m, &s);
      tmp.first = h * 3600 + m * 60 + s;
      scanf("%d:%d:%d", &h, &m, &s);
      tmp.second = h * 3600 + m * 60 + s;
      t.push_back(tmp);
    }

    int ans = 0, movin = 0, ind = 0;
    queue<int> q;
    for(int now=0; now <= ADAY; now++){
      while(!q.empty() && now == q.front()){
        movin--;
        q.pop();
      }
      while(ind < n && now == t[ind].first){
        q.push(t[ind].second);
        movin++;
        ind++;
        ans = max(ans, movin);
      }
    }
    cout << ans << endl;
  }
  return 0;
}