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<iostream>
#include<vector>
#include<algorithm>
using namespace std;
int main(){
    int n;
    while(scanf("%d",&n),n){
        int imoss[60*60*24+100]={0};
        for(int i=0;i<n;i++){
            int t,m,s;
            scanf("%d:%d:%d",&t,&m,&s);
            imoss[t*3600+m*60+s]++;
            scanf("%d:%d:%d",&t,&m,&s);
            imoss[t*3600+m*60+s]--;
        }
        for(int i=1;i<=24*60*60;i++)imoss[i]+=imoss[i-1];
        int ma=0;
        for(int i=0;i<=24*60*60;i++)ma=max(ma,imoss[i]);
        printf("%d\n",ma);
    }
    return 0;
}

C++: #include <algorithm>
#include <cstdio>
#include <iostream>
#include <string>
#include <utility>
#include <vector>
using namespace std;
int main() {
  int n, ans, k, t[6];
  vector< pair<int, int> > T;
  while (cin >> n, n) {
    for (int i = 0; i < n; ++i) {
      scanf("%d:%d:%d %d:%d:%d",&t[0],&t[1],&t[2],&t[3],&t[4],&t[5]);
      T.push_back(make_pair(t[0]*3600+t[1]*60+t[2], 1));
      T.push_back(make_pair(t[3]*3600+t[4]*60+t[5], -1));
    }
    ans = 0;
    k = 0;
    sort(T.begin(), T.end());
    for (int i = 0; i < 2*n; ++i) {
      k += T[i].second;
      ans = max(ans, k);
    }
    cout << ans << endl;
  }
  return 0;
}

C++: #include <iostream>
using namespace std;

int main() {
  int n;
  int res = 0;
  int h1, m1, s1;
  int h2, m2, s2;

  while(cin >> n, n!=0){
    signed int time[24*3600+60*60+60] = {0};
    for(int i = 0; i < n; i++) {
      scanf("%d:%d:%d", &h1, &m1, &s1);
      scanf("%d:%d:%d", &h2, &m2, &s2);
      time[h1*3600+m1*60+s1]++;
      time[h2*3600+m2*60+s2]--;
    }

    for(int i = 0; i < 24*3600+60*60+60; i++) {
      time[i+1]+=time[i];
      if(res < time[i+1])
        res = time[i+1];
    }
    cout << res << endl;
  }
  return 0;
}

C++: #include <iostream>
#include <algorithm>
#include <cstdio>
#include <cstring>
using namespace std;

int main(){
	int n;
	while(cin>>n,n){
		int data[86450]={0},a,b,c,A,B,C,ans=0;
		for(;n>0;n--){
			scanf("%d:%d:%d %d:%d:%d",&a,&b,&c,&A,&B,&C);
			b+=(a*60);
			c+=(b*60);
			B+=(A*60);
			C+=(B*60);
			data[c]++;
			data[C]--;
		}
		for(int i=1;i<86440;i++){
			data[i]+=data[i-1];
		}
		for(int i=0;i<86445;i++){
			ans=max(ans,data[i]);
		}
		cout<<ans<<endl;
	}
	
	
	
	
	return 0;
}

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

template <class T, class U>
T lexical_cast(const U& from) {
    stringstream ss;
    ss << from;
    T to;
    ss >> to;
    return to;
}

int time2int(const string& str) {
    int h = lexical_cast<int>(str.substr(0,2));
    int m = lexical_cast<int>(str.substr(3,2));
    int s = lexical_cast<int>(str.substr(5,2));
    return h * 60 * 60 + m * 60 + s;
}

int main() {
    for(int N; cin >> N, N; ) {
        vector<int> v(60*60*24, 0);
        for(int i = 0; i < N; i++) {
            string s, e; cin >> s >> e;
            int ss = time2int(s);
            int ee = time2int(e);
            for(int j = ss; j < ee; j++) {
                v[j]++;
            }
        }
        cout << *max_element(v.begin(), v.end()) << endl;
    }
}

C++: #include <iostream>
#include <cstdio>
#include <map>
using namespace std;
int main() {
	int n;
	std::map<int, int> tv;
	for (;;) {
		cin >> n;
		if (!n) break;
		for (int i = 0; i < n; ++i) {
			int h, m, s1, s2;
			scanf("%2d:%2d%:%2d", &h, &m, &s1);
			m += h * 60;
			s1 += m * 60;
			scanf("%2d:%2d:%2d", &h, &m, &s2);
			m += h * 60;
			s2 += m * 60;
			++tv[s1];
			--tv[s2];
		}
		int c = 0, max = 0;
		for (auto i : tv) {
			c += i.second;
			if (max < c) max = c;
		}
		std::cout << max << std::endl;
	}
	return 0;
}

C++: #include <iostream>
#include <string>
#include <algorithm>
#include <functional>
#include <vector>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <cmath>
using namespace std;
typedef long long ll;
typedef pair<int,int> pint;
typedef vector<int> vint;
typedef vector<pint> vpint;
#define mp make_pair
#define fi first
#define se second
#define all(v) (v).begin(),(v).end()
#define rep(i,n) for(int i=0;i<(n);i++)
#define reps(i,f,n) for(int i=(f);i<(n);i++)

void slove(int n){
	vector<int> v(86410);
	rep(i, 86410) v[i] = 0;//?????????
	rep(i, n){
		string s, e;
		cin >> s >> e;
		//?§???°?????????
		int start = 36000 * (s[0] - '0') + 3600 * (s[1] - '0') 
					+ 600 * (s[3] - '0') + 60 * (s[4] - '0')
					+ 10 * (s[6] - '0') + 1 * (s[7] - '0');
		int end = 36000 * (e[0] - '0') + 3600 * (e[1] - '0') 
					+ 600 * (e[3] - '0') + 60 * (e[4] - '0')
					+ 10 * (e[6] - '0') + 1 * (e[7] - '0') - 1;
		
		v[start]++;
		v[end]--;
	}
	int ans = 0;
	int now = 0;
	reps(i, 1, 86410){
		v[i] += v[i - 1];
		//now += v[i];
		ans = max(ans, v[i]);
	}
	printf("%d\n", ans);
}
int main(void){
	rep(i, 1000000){
		int n; scanf("%d", &n);
		if(n == 0) break;
		slove(n);
	}
	return 0;
}