#include <stdio.h>

int is_greater_than_20 ( int x ){  printf( "FIRST\n"  ); return x > 20 ; }
int is_less_than_30    ( int x ){  printf( "SECOND\n" ); return x < 30 ; }

#define and(a,b) ({a ? b : 0;})

int main(int argc, char **argv)
{
  int age ;
  for( age = 15 ; age < 40 ; age += 10 )
    if(  and( is_greater_than_20(age) , is_less_than_30(age) )  )
      printf( "%d: true\n\n" , age );
    else
      printf( "%d: false\n\n" , age );
  return 0;
}

FIRST
15: false

FIRST
SECOND
25: true

FIRST
SECOND
35: false