/**
 *  Osaki (Problem B, Practice Contest for Japan Domestic, 2007-06-24)
 *  by Kenji Inoue, 2007-06-25
 **/

#include <iostream>
#include <string>
#include <vector>

using namespace std;

struct Event {
  string time;
  int type; // 0 = start, 1 = end
  int operator<(const Event &a) const {
    return time != a.time ? time < a.time
                          : type > a.type;
  }
};

int main() {
  int n;
  while (cin >> n, n) {
    vector<Event> ev;
    for (int i=0; i<n; i++) {
      string s, e;
      cin >> s >> e;
      Event start = {s, 0};
      Event end   = {e, 1};
      ev.push_back(start);
      ev.push_back(end);
    }
    sort(ev.begin(), ev.end());

    int max = 0, current = 0;
    for (int i=0; i<ev.size(); i++) {
      if (ev[i].type == 0) { current++; } else { current--; }
      if (current > max) { max = current; }
    }
    cout << max << endl;
  }

  return 0;
}