import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);

        int N = scanner.nextInt();
        int[][] arr = new int[N][2];

        for (int i = 0; i < N; i ++) {
            arr[i][0] = scanner.nextInt();
            arr[i][1] = scanner.nextInt();
        }

        int mv = 0;

        for (int i = 0; i < N; i ++) {
            int[] cov = new int[1001];

            for (int j = 0; j < N; j ++) {
                if (j == i)
                    continue;
                for (int k = arr[j][0]; k < arr[j][1]; k ++)
                    cov[k] = 1;
            }

            int cur = 0;
            for (int j = 0; j <= 1000; j ++) {
                cur += cov[j];
            }

            mv = Math.max(mv, cur);
        }

        System.out.println(mv);
    }

}