c++ del 1 al cienmil romano

c++ programa que convierte de numero arabicos (normales ) a romanos
si tengo faltas de orotgrafias que les valga jejejee lo q importa es el programa

#include <stdio.h>
#include <stdlib.h>
/*HECHO POR ANGEL ROSALES RIFANDO Y CONTROLANDO*/
int main()
{
int num,entero,res;
char letra;

printf( "Introduce un numero " );
scanf( "%i", &num );
/* Dividimos por 10000 */
entero = num/10000;
res = num%10000;
switch( entero )
{
case 1: printf( "_"; printf( "n" );
printf( "X" ); break;
case 2: printf( "__"; printf( "n" );
printf( "XX" ); break;
case 3: printf( "___"; printf( "n" );
printf( "XXX" ); break;
case 4: printf( "__"; printf( "n" );
printf( "XL" ); break;
case 5: printf( "_"; printf( "n" );
printf( "L";break;
case 6: printf( "__"; printf( "n" );
printf( "LX" ); break;
case 7: printf( "___"; printf( "n" );
printf( "LXX" ); break;
case 8: printf( "____"; printf( "n" );
printf( "LXXX" ); break;
case 9: printf( "__"; printf( "n" );
printf( "XC" ); break;
case 10: printf( "_"; printf( "n" );
printf( "C" ); break;
}
/* Dividimos por 1000 SMF13*/
entero = num/1000;
res = num%1000;
switch( entero )
{
case 1: printf( "M" ); break;
case 2: printf( "MM" ); break;
case 3: printf( "MMM" ); break;
case 4: printf( " _"; printf( "n" );
printf( "MV" ); break;
case 5: printf( "_"; printf( "n" );
printf( "V";break;
case 6: printf( "_"; printf( "n" );
printf( "VM" ); break;
case 7: printf( "_"; printf( "n" );
printf( "VMM" ); break;
case 8: printf( "_"; printf( "n" );
printf( "VMMM" ); break;
case 9: printf( "__"; printf( "n" );
printf( "MX" ); break;
}
/* Dividimos por 100 CLOWN*/
entero = num/100;
res = num%100;
switch( entero )
{
case 1: printf( "C" ); break;
case 2: printf( "CC" ); break;
case 3: printf( "CCC" ); break;
case 4: printf( "CD" ); break;
case 5: printf( "D" ); break;
case 6: printf( "DC" ); break;
case 7: printf( "DCC" ); break;
case 8: printf( "DCCC" ); break;
case 9: printf( "CM" ); break;
}
/*Dividimos por 10 SS13*/
entero = res/10;
res=res%10;
switch( entero )
{
case 1: printf( "X" ); break;
case 2: printf( "XX" ); break;
case 3: printf( "XXX" ); break;
case 4: printf( "XL" ); break;
case 5: printf( "L" ); break;
case 6: printf( "LX" ); break;
case 7: printf( "LXX" ); break;
case 8: printf( "LXXX" ); break;
case 9: printf( "XC" ); break;
}

switch( res )
{
case 1: printf( "I" ); break;
case 2: printf( "II" ); break;
case 3: printf( "III" ); break;
case 4: printf( "IV" ); break;
case 5: printf( "V" ); break;
case 6: printf( "VI" ); break;
case 7: printf( "VII" ); break;
case 8: printf( "VIII" ); break;
case 9: printf( "IX" ); break;
}
/*HECHO POR ANGEL ROSALES RIFANDO Y CONTROLANDO*/
printf( "n" );
system("pause";
}