import java.util.Scanner;

public class Main {
    static Scanner scn = new Scanner(System.in);
    static private int n = scn.nextInt();
    static private int[] dp = new int[1440];
    public static void main(String[] args) {
        scn.nextLine();
        readData();
        int max = 0;
        int inside = 0;
        for(int i = 0; i < 1440; i++){
            inside += dp[i];
            max = Math.max(max, inside);
        }
        System.out.println(max);
    }
    private static void readData() {
        // TODO Auto-generated method stub
        for(int i = 0; i < n; i++){
            String s = scn.nextLine();
            dp[toIntIn(s)]++;
            dp[toIntOut(s)+1]--;
        }
    }
    private static int toIntOut(String s) {
        // TODO Auto-generated method stub
        int a = 0;
        a += 600*((int)s.charAt(6)-(int)'0');
        a += 60*((int)s.charAt(7)-(int)'0');
        a += 10*((int)s.charAt(9)-(int)'0');
        a += (int)s.charAt(10)-(int)'0';
        return a;
    }
    private static int toIntIn(String s) {
        // TODO Auto-generated method stub
        int a = 0;
        a += 600*((int)s.charAt(0)-(int)'0');
        a += 60*((int)s.charAt(1)-(int)'0');
        a += 10*((int)s.charAt(3)-(int)'0');
        a += (int)s.charAt(4)-(int)'0';
        return a;
    }
}