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 <iostream>
#include <sstream>
#include <fstream>
#include <string>
#include <vector>
#include <deque>
#include <queue>
#include <stack>
#include <set>
#include <map>
#include <algorithm>
#include <functional>
#include <utility>
#include <bitset>
#include <cmath>
#include <cstdlib>
#include <ctime>
#include <cstdio>

#define rep(i, n) for(int (i) = 0; (i) < (n); (i)++)

class Solve {
public:
	Solve() {};
	~Solve() {};

	void solver() {
		std::vector<int> results;
		while (1) {
			int n;
			std::cin >> n;
			if (!n) break;

			std::string str;
			rep(i, n) {
				times.push_back(std::make_pair(0, 0));
				std::cin >> str;
				times.back().first = std::stoi(str.substr(6, 2)) + std::stoi(str.substr(3, 2)) * 60 + std::stoi(str.substr(0, 2)) * 3600;
				std::cin >> str;
				times.back().second = std::stoi(str.substr(6, 2)) + std::stoi(str.substr(3, 2)) * 60 + std::stoi(str.substr(0, 2)) * 3600;
			}
			//
			std::reverse(times.begin(), times.end());
			//???????????????????????????
			std::vector<int> usingTrain; //int?????°?????????
			int maxTrain = 0;
			while (!times.empty()) {
				int leave = times.back().first;
				int arrive = times.back().second; times.pop_back();
				//??°???????????????????????????
				std::sort(usingTrain.begin(), usingTrain.end(), std::greater<int>());
				//????????°???
				if (!usingTrain.empty()) {
					//????????°?????????????????????????????°???
					if (leave >= usingTrain.back()) {
						usingTrain.pop_back();
					}
				}
				//??????
				usingTrain.push_back(arrive);
				if (maxTrain < usingTrain.size()) maxTrain = usingTrain.size();
			}
			results.push_back(maxTrain);
		}
		for (auto& x : results) {
			std::cout << x << std::endl;
		}
	}
private:
	std::vector<std::pair<int, int>> times;
};

int main() {
	Solve solve;
	solve.solver();
	getchar(); getchar();
	return 0;
}

C++: #include <algorithm>
#include <bitset>
#include <cassert>
#include <cmath>
#include <functional>
#include <iomanip>
#include <iostream>
#include <map>
#include <numeric>
#include <queue>
#include <unordered_map>
#include <vector>
#include <string.h>
#include <set>
#include <stack>

using namespace std;

#define COUT(x) cout << #x << " = " << (x) << " (L" << __LINE__ << ")" << endl

template<class T> void printvec(const vector<T>& v) {
  for (auto x : v) { cout << x << " "; }
  cout << endl;
}
template<class T> void printtree(const vector< vector<T> >& tree) {
  for (long long i = 0; i < tree.size(); ++i) {
    cout << i + 1 << ": "; printvec(tree[i]);
  }
}
template<class T, class U> void printmap(const map<T, U>& mp) {
  for (auto x : mp) { cout << x.first << "=>" << x.second << endl; }
}

template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return true; } return false; }
template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return true; } return false; }

#define rep(i, n) for(ll i = 0; i < n; ++i)
#define all(s) s.begin(), s.end()
#define sz(x) (ll)(x).size()
#define fr first
#define sc second
#define mp make_pair
#define pb push_back
#define eb emplace_back

typedef long long ll;
typedef unsigned long long ull;
typedef pair<ll, ll> P;
typedef tuple<ll, ll, ll> triple;
typedef double D;
typedef vector<ll> vl;
typedef vector<P> vp;

const ll INF = 1e9;
const ll MOD = 1000000007;  // 1e9 + 7

ll to_i(string&s, int i1) {
  ll ret = 0;
  ret += (s[i1]-'0')*10;
  ret += (s[i1+1]-'0');
  return ret;
}

ll to_time(string& s) {
  ll hr = to_i(s,0);
  ll mn = to_i(s,3);
  ll sc = to_i(s,6);
  return hr*3600 + mn*60 + sc;
}

void solve(ll n) {
  vector<pair<string,string>> a(n); // pair of <start, end>
  rep(i,n) {
    cin >> a[i].first >> a[i].second;
  }
  vector<pair<ll,ll>> b(n); // pair of <end, start>
  rep(i,n) {
    b[i] = pair<ll,ll>(to_time(a[i].second), -to_time(a[i].first));
  }
  sort(all(b));

  map<ll,ll> mp; // collection of end time
  for (auto& p : b) {
    if (mp.empty()) {
      ++mp[p.first];
      continue;
    }
    // Here, mp is not empty

    auto it = mp.upper_bound(-p.second);
    // Here, prev(it) is insertion point.
    if (it == mp.begin()) { // Here, we can not use same train. Add new train.
      ++mp[p.first];
    } else { // Here, we can use prev(it) as same train.
      auto pit = prev(it);
      --(pit->second);
      if (pit->second == 0) { // count is 0
        mp.erase(pit);
      }
      ++mp[p.first];
    }
  }

  ll ans = 0;
  for (auto& p : mp) {
    ans += p.second;
  }
  cout << ans << endl;
}

int main(int argc, char** argv) {
  cin.tie(NULL);
  cout.tie(NULL);
  ios_base::sync_with_stdio(false);
  //cout << setprecision(10) << fixed;

  while (true) {
    ll n;
    cin >> n;
    if (n == 0) { break; }
    solve(n);
  }
}