#include <iostream>

using namespace std;

// You MUST accept a string as the argument
int Convert_to_Dec ( const char *hex );

// You MUST return a string
char *Convert_to_Hex ( int dec );

int main()
{
 cout<< Convert_to_Dec ( "1B" ) <<endl;
 cout<< Convert_to_Hex ( 27 ) <<endl;
}

int Convert_to_Dec ( const char *hex )
{
 int ret = 0;

 while ( *hex != '\0' ) {
  if ( *hex >= '0' && *hex <= '9' )
   ret = 10 * ret + ( *hex - '0' );
  else {
   // Assuming ASCII
   ret = 16 * ret + ( *hex - 'A' + 10 );
  }
  ++hex;
 }

 return ret;
}

char *Convert_to_Hex ( int dec )
{
 static char hex[20];
 int i = 0, j = 0;

 // Build the string
 while ( dec != 0 ) {
  hex[i++] = "0123456789ABCDEF"[dec % 16];
  dec /= 16;
 }

 // Make it a valid string
 hex[i] = '\0';

 // Reverse the string
 while ( j < i ) {
  char temp = hex[j];
  hex[j++] = hex[--i];
  hex[i] = temp;
 }

 return hex;
}