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 <vector>
#define MAX(a,b) ((a>b)?a:b)
using namespace std;

struct times{
    int h;
    int m;
    int s;
    int operator-(const times& a) const {
        return(h*3600+m*60+s-a.h*3600-a.m*60-a.s);
    }
};
struct tp{
    struct times fr;
    struct times to;
    int tno;
};
bool iscrossed(struct tp *a,struct tp *b){
    if((b->fr-a->fr)>=0 && (a->to-b->fr)>0){return true;}
    if((b->to-a->fr)>0 && (a->to-b->to)>=0){return true;}
    return false;
}

int main(){
    vector<tp> trs;
    int i,n,m,f;
    while(1){
        scanf("%d",&n);
        if(!n){break;}
        for(i=0;i<n;i++){
            struct times fr,to;
            scanf("%d:%d:%d",&fr.h,&fr.m,&fr.s);
            scanf("%d:%d:%d",&to.h,&to.m,&to.s);
            struct tp tms={fr,to,0};
            if(trs.empty()){
                tms.tno=1;
                trs.push_back(tms);
            }
            else{
                m=0;f=0;
                for(auto it=trs.begin();it!=trs.end();it++){
                    if(iscrossed(&tms,&(*it))){m=MAX(m,(*it).tno);}
                    else{tms.tno=(*it).tno;f=1;break;}
                }
                if(m && !f){tms.tno=m+1;}
                trs.push_back(tms);
            }
        }
        m=0;
        for(auto it=trs.begin();it!=trs.end();it++){
            m=MAX(m,(*it).tno);
        }
        printf("%d\n",m);
    }
    return 0;
}

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

int main()
{
	int n;
	while (cin >> n, n) {
		vector<string> go(n), come(n);
		go.reserve(n); come.reserve(n);
		for (int i = 0; i < n; i++) {
			cin >> go[i];
			cin >> come[i];
		}
		sort(go.begin(), go.end());
		sort(come.begin(), come.end());
		int res = 0, tmp = 0, g = 0, c = 0;
		while (g != n || c != n) {
			if (g == n) {
				c++;
				tmp--;
			}
			else if (c == n) {
				g++;
				tmp++;
			}
			else {
				if (go[g] < come[c]) {
					g++;
					tmp++;
				}
				else {
					c++;
					tmp--;
				}
			}
			if (tmp > res)
				res = tmp;
		}
		cout << res << endl;
	}
	return 0;
}

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

#define fi first
#define se second
#define repl(i,a,b) for(int i=(int)(a);i<(int)(b);i++)
#define repr(i,n) for(int i=(int)(n-1);i>=0;i--)
#define rep(i,n) repl(i,0,n)
#define each(itr,v) for(auto itr:v)
#define pb(s) push_back(s)
#define all(x) (x).begin(),(x).end()
#define dbg(x) cout << #x" = " << x << endl
#define print(x) cout << x << endl
#define maxch(x,y) x=max(x,y)
#define minch(x,y) x=min(x,y)
#define uni(x) x.erase(unique(all(x)),x.end())
#define exist(x,y) (find(all(x),y)!=x.end())
#define bcnt(x) bitset<32>(x).count()

typedef long long ll;
typedef unsigned long long ull;
typedef pair<int, int> P;
typedef pair<P, int> PPI;
typedef pair<int, P> PIP;
typedef pair<ll, ll> PL;
typedef pair<P, ll> PPL;
typedef set<int> S;

#define INF INT_MAX/3
#define MAX_N 1000000001


int main(){
  cin.sync_with_stdio(false);
  int n;
  while(cin >> n, n) {
    string s;
    int time[24 * 3600] = {};
    rep(i, n) {
      cin >> s;
      time[stoi(s.substr(0, 2)) * 3600 + stoi(s.substr(3, 2)) * 60 + stoi(s.substr(6, 2))]++;
      cin >> s;
      time[stoi(s.substr(0, 2)) * 3600 + stoi(s.substr(3, 2)) * 60 + stoi(s.substr(6, 2))]--;
    }
    int maxi = 0, tmp = 0;
    rep(i, 24 * 3600) {
      tmp += time[i];
      maxch(maxi, tmp);
    }
    cout << maxi << endl;
  }

  return 0;
}

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


#define M  24*60*60
int table[M];


int main(){
  int n;
  string str;
  while(cin >> n, n){

    for(int i = 0; i < n; i++){
      cin >> str;
      int s = std::stoi(str.substr(0,2))*60*60 + std::stoi(str.substr(3,2))*60
	+ std::stoi(str.substr(6,2));
      table[s]++;
      cin >> str;
      int e = std::stoi(str.substr(0,2))*60*60 + std::stoi(str.substr(3,2))*60
	+ std::stoi(str.substr(6,2));
      table[e]--;
    }
    for(int i = 1; i < M; i++){
      table[i] += table[i-1];
    }
    int max = 0;
    for(int i = 0; i < M; i++){
      if(max < table[i]) max = table[i];
    }
    cout << max << endl;
  }


}

C++: #include <iostream>
#include <map>
#include <string>

using namespace std;

int main(int argc, char const *argv[])
{
	int n;
	string s1,s2;
	int cnt;
	int max;

	while(1){
		cin>>n;
		if(n==0) break;

		multimap<string,int> mp;

		for(int i1=0;i1<n;i1++){
			cin>>s1>>s2;
			mp.insert(make_pair(s1,1));
			mp.insert(make_pair(s2,0));
		}

		cnt=0;
		max=0;
		for(multimap<string,int>::iterator it=mp.begin(); it!=mp.end();it++){
			if((*it).second==1) cnt++;
			else if((*it).second==0) cnt--;

			if(max<cnt) max=cnt;
		}

		cout<<max<<endl;
	}
	return 0;
}

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

bool solve(){
    int n;
    cin >> n;
    if(n == 0) return true;
    vector<pair<string,int> > ls;
    for(int i=0;i<n;i++){
        string s, t;
        cin >> s >> t;
        ls.emplace_back(make_pair(s,1));
        ls.emplace_back(make_pair(t,-1));
    }
    sort(ls.begin(), ls.end());
    int cnt = 0, ans = 0;
    for(auto p : ls){
        cnt += p.second;
        ans = max(ans, cnt);
    }
    cout << ans << endl;
    return false;
}

int main(){
    while(!solve());
    return 0;
}