# include <stdio.h>

# define YES 1
# define NO 0
//
//  Program 13.1, Stephen Kochan, Programming in C.
//
int main ( void );
int isEven ( int number );

int main ( void )
{
  if ( isEven ( 17 ) == YES )
  {
    printf ( "17 is even.\n" );
  }
  else
  {
    printf ( "17 is odd.\n" );
  }

  if ( isEven ( 20 ) == YES )
  {
    printf ( "20 is even.\n" );
  }
  else
  {
    printf ( "20 is odd.\n" );
  }

  return 0;
}


int isEven ( int number )
{
  int answer;

  if ( number %2 == 0 )
  {
    answer = YES;
  }
  else
  {
    answer = NO;
  }
  return answer;
}