using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.IO;//pt fisiere

namespace intervale
{
    class interval
    {
        private int a, b;//capetele intervalului

        //proprietati
        public int A
        {
            get { return a; }
            set { a = value; }
        }
        public int B
        {
            get { return b; }
            set { b = value; }
        }

        //verificare disjuncte
        public bool disjunct(interval b)
        {
            return this.a > b.B || b.A > this.b;
        }

        //supraincarcare metoda ToString
        public override string ToString()
        {
            return a + " " + b;
        }
    }

    class Program
    {
        static void citire(out interval[] A, out int n)
        {
            StreamReader fin = new StreamReader("intervale.in");
            n = int.Parse(fin.ReadLine());//citesc n
            A = new interval[n + 1];//creez tabloul de intervale
            for(int i=1;i<=n;i++)
            {
                string l = fin.ReadLine(); //citesc un rand
                string[] s = l.Split();//il despart
                interval a = new interval();//creez un interval
                a.A = int.Parse(s[0]);//capatul stang
                a.B = int.Parse(s[1]);//capatul drept
                A[i] = a;//pun in vector
            }
            fin.Close();
        }

        static void afisare(interval[] A, int n)
        {
            StreamWriter fout = new StreamWriter("intervale.out");
            fout.WriteLine(n);
            for (int i = 1; i <= n; i++)
                fout.WriteLine(A[i].ToString());
            fout.Close();
        }

        static void Main(string[] args)
        {
            int n,m=0;
            interval[] A,B;
            citire(out A, out n);
            B=new interval[n+1];
            for (int i = 1; i <= n; i++)
            {// pt fiecare interval din a
                int k = 0;
                for (int j = 1; j <= n; j++)//parcurgem
                    if (A[i].disjunct(A[j])) 
                           k++;//le numar pe cele disjuncte
                if (k == n - 1)//daca n-1 sunt disjuncte 
                    B[++m] = A[i];//il punem in B
            }
            afisare(B, m);
            Console.ReadKey();
        }
    }
}