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 range(i,a,b) for(int i = (a); i < (b); i++)
#define rep(i,b) for(int i = 0; i < (b); i++)
#define all(a) (a).begin(), (a).end()
#define show(x)  cerr << #x << " = " << (x) << endl;
using namespace std;

//テ・ツ個コテゥツ鳴鄭[a,b]テ」ツ?ィテ・ツ個コテゥツ鳴釘[c,d]テ」ツ?ョテゥツ鳴「テ、ツソツ?
int intervalState(int a, int b, int c, int d){
    if(a <= c && b <= c) return 0;            //A < B
    else if(a >= d && b >= d) return 1;       //A > B
    else if(a <= c && d <= b) return 2;     //A -> B
    else if(c < a && b < d) return 3;       //B -> A
    else if(a <= c && b < d) return 4;      //A <= B
    else if(c < a && d <= b) return 5;      //A >= B
    return -1;
}

bool check(vector<pair<int,int>> v, pair<int,int> p){
    rep(i,v.size()){
        //cout << v[i].first << ' ' << v[i].second<< endl;
        int tmp = intervalState(v[i].first,v[i].second,p.first,p.second);
        if(not(tmp == 0 || tmp == 1)) return false;
    }
    return true;
}

int main(){
    int n;
    while(cin >> n,n){
        pair<int,int> p[10005];
        rep(i,n){
            int h, m, s;
            char g;
            cin >> h >> g >> m >> g >> s;
            int x = h * 60 * 60 + m * 60 + s;

            cin >> h >> g >> m >> g >> s;
            int y = h * 60 * 60 + m * 60 + s;

            p[i] = make_pair(x,y);
        }
        sort(p, p + n);

        vector<pair<int,int>> v[10005];
        rep(i,n){
            int j = 0;
            //cout << p[i].first << ' ' << p[i].second << endl;
            while(true){
                if(v[j].empty()) {
                    v[j].emplace_back(p[i]);
                    break;
                }else{
                    if(check(v[j],p[i])){
                        v[j].emplace_back(p[i]);
                        break;
                    }else{
                        j++;
                    }
                }
            }
        }
        int ans = 0;
        rep(i,10001){
            if(v[i].empty()) break;
            ans++;
        }
        cout << ans << endl;
    }
}

C++: #include <iostream>
#include <vector>
#include <queue>
#include <string>
#include <algorithm>
#include <cmath>

using namespace std;

int main() {
	int n;
	while (cin >> n) {
		if (n == 0) {
			break;
		}
		int h, m, s;
		int h2, m2, s2;
		char c;
		vector<int> mm(100000, 0);
		for (int i = 0; i < n; i++) {
			cin >> h >> c >> m >> c >> s >> h2 >> c >> m2 >> c >> s2;
			//cout << h << ' ' << m << ' ' << s << ' ' << h2 << ' ' << m2 << ' ' << s2 << endl;
			int a = h * 3600 + m * 60 + s;
			int b = h2 * 3600 + m2 * 60 + s2;
			//cout << a << ' ' << b << endl;
			mm[a]++;
			mm[b]--;
		}
		int MAX = mm[0];
		for (int i = 1; i < 100000; i++) {
			mm[i] += mm[i - 1];
			MAX = max(MAX, mm[i]);
		}
		cout << MAX << endl;
	}
	return 0;
}

C++: #include<iostream>
#include<cstdio>
#include<algorithm>
using namespace std;
#define MAX_N 100000
int x[MAX_N];

int main() {
	int n, a, b, c, d, e, maxn = 0;;
	while (true) {
		for (int i = 0; i < MAX_N; i++) {
			x[i] = 0;
		}
		cin >> n; maxn = 0;
		if (n == 0) { break; }
		for (int i = 0; i < n; i++) {
			scanf("%02d:%02d:%02d", a, b, c);
			d = a * 3600 + b * 60 + c;
			scanf("%02d:%02d:%02d", a, b, c);
			e = a * 3600 + b * 60 + c;
			x[d]++; x[e]--;
		}
		for (int i = 1; i < 99999; i++) {
			x[i] += x[i - 1];
			maxn = max(maxn, x[i]);
		}
		cout << maxn << endl;
	}
}

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[87000];

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

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

		rep(i,0,87000) t[i] = 0;
		rep(i,0,n) {
			int h,m,s;
			scanf("%d:%d:%d", &h, &m, &s);
			t[h*3600 + m*60 + s]++;
			scanf("%d:%d:%d", &h, &m, &s);
			t[h*3600 + m*60 + s]--;
		}

		int ans = -1, tmp = 0;
		rep(i,0,87000) {
			tmp += t[i];
			ans = max(ans, tmp);
		}
		cout << ans << endl;
	}
	return 0;
}

C++: #include <cstdio>
#include <iostream>
#include <algorithm>
#include <map>
#include <vector>
using namespace std;
vector<pair<int,int> > v[2];
int main(void){
  int res;
  int n,f;
  while(cin >> n && n){
    f = res = 0;
    v[0].clear();
    for(int i = 0; i < n; i++){
      int a,b,c,d;
      scanf("%d:%d:%d",&a,&b,&c);
      d = a*3600 + b*60 + c;
      scanf("%d:%d:%d",&a,&b,&c);
      c = a*3600 + b*60 + c;
      v[0].push_back(make_pair(d,c));
    }

    sort(v[0].begin(),v[0].end());

    while((int)v[f].size()){
      res++;
      int b = v[f][0].second;
      v[(f+1)%2].clear();
      for(int i = 1; i < (int)v[f].size(); i++){
	if(v[f][i].first < b){
	  v[(f+1)%2].push_back(v[f][i]);
	}else{
	  b = v[f][i].second;
	}
      }
      f = (f+1)%2;
    }
    cout << res << endl;
  }
}