//---------------------------------------------------------------------------
#include <stdio.h>
#include <stdlib.h>
//---------------------------------------------------------------------------

const unsigned int MAXIMO = 60000;

void GeneraAleatorio(char *Entrada,int N)
{
FILE *Output;
unsigned int Ini,Fin;
int i;

Output = fopen(Entrada,"w+t");

fprintf(Output,"%d\n",N);
for(i = 0; i < N; i++)
  {
  Ini = random(MAXIMO - 1);
  Fin = random(MAXIMO - Ini - 1);
  Fin += Ini+1;
  fprintf(Output,"%u %u\n",Ini+1,Fin+1);
  }

fclose(Output);
}
///**************************************************************************
void QuickSort(unsigned int *A,int Lower,int Higher)
{
int Lo, Hi, Mid, T;

if( Lower >= Higher )
  { return; }

Lo = Lower;
Hi = Higher;
Mid = A[(Lo+Hi)/2];
do
 {
 while( A[Lo] < Mid )
		{ Lo++; }
 while( A[Hi] > Mid )
		{ Hi--; }
 if( Lo <= Hi )
	{
	// Intercambiamos los extremos.
	T = A[Lo];
	A[Lo] = A[Hi];
	A[Hi] = T;

	Lo++;
	Hi--;
	}
 } while (Lo < Hi);

QuickSort(A,Lower,Hi);
QuickSort(A,Lo,Higher);
}
///**************************************************************************
void Resuelve(int N,unsigned int *Ini,unsigned int *Fin)
{
FILE *Output;
int PosIntervalo;
unsigned int i,Flag,Maximo,Count,PosIni,PosFin;
unsigned int *Intervalo;

QuickSort(Ini,0,N-1);
QuickSort(Fin,0,N-1);

Intervalo = new unsigned int[20000];
PosIni = 0;
PosFin = 0;
Maximo = 0;
Count = 0;
Flag = 0;
PosIntervalo = 0;


for(i = 0; i < Fin[N-1]+1; i++)
  {
  while( PosIni < N && Ini[PosIni] == i )
	 {
	 PosIni++;
	 Count++;
	 }
  while( PosFin < N && Fin[PosFin] == i )
	 {
	 PosFin++;
	 Count--;
	 }

  if( Maximo < Count )
	 {
	 PosIntervalo = 1;
	 Intervalo[0] = i;
	 Maximo = Count;
	 Flag = 1;
	 }
  else if( Maximo == Count && Flag == 0 )
	 {
	 Intervalo[PosIntervalo] = i;
	 PosIntervalo++;
	 Flag = 1;
	 }
  else if( Maximo > Count && Flag == 1 )
	 {
	 Intervalo[PosIntervalo] = i;
	 PosIntervalo++;
    	 Flag = 0;
    	 }
  }

Output = fopen("Output.txt","w+t");

fprintf(Output,"%u\n",Maximo);
for(i = 0; i < PosIntervalo; i+=2)
  { fprintf(Output,"%u %u ",Intervalo[i],Intervalo[i+1]); }

delete[] Intervalo;
fclose(Output);
}
///**************************************************************************
int main(void)
{
FILE *Input;
int i,N;
unsigned int *Ini,*Fin;

//randomize();
//GeneraAleatorio("input9.txt",10000);

Input = fopen("Input.txt","r+t");
fscanf(Input,"%d",&N);
Ini = new unsigned int[N];
Fin = new unsigned int[N];
for(i = 0; i < N; i++)
  { fscanf(Input,"%u %u",&Ini[i],&Fin[i]); }
fclose(Input);

Resuelve(N,Ini,Fin);

delete[] Ini;
delete[] Fin;
		  return 0;
}
//---------------------------------------------------------------------------