%{
#define YY_INPUT(buf,result,max_size) \
   { int digit ; \
     int c = getc( yyin ) ; \
     result = c == EOF ? 0 : 1 ; \
     if( c == '%' ) { \
        c = getc( yyin ) ; \
        digit = c >= 'A' ? (( c & 0xdf ) - 'A' ) + 10 : c - '0' ; \
        digit *= 16 ; \
        c = getc( yyin ) ; \
        digit += c >= 'A' ? (( c & 0xdf ) - 'A' ) + 10 : c - '0' ; \
        buf[0] = (char) digit ; \
     } \
     else if( c == '+' ) \
        buf[0] = ' ' ; \
     else \
        buf[0] = (char) c ; \
   }

%}
WS	[ \t]
%%
"answer4-2=A"\&?	{ send_file( "ans4-2.wronga" ) ; return( 1 ) ; }
"answer4-2=B"\&?	{ send_file( "ans4-2.wrongb" ) ; return( 1 ) ; }
"answer4-2=C"\&?	{ send_file( "ans4-2.wrongc" ) ; return( 1 ) ; }
"answer4-2=D"\&?	{ send_file( "ans4-2.right" ) ; return( 1 ) ; }
%%
#include <stdio.h>

main()
{
   if( !yylex())
      send_file( "ans4-2.none" ) ;
}

send_file( s )
char *s ;
{
   FILE *fp ;
   char buf[81] ;

   printf( "Content-type: text/html\n\n" ) ;
   fp = fopen( s, "r" ) ;
   if( fp ) {
      while( fgets( buf, 80, fp )) {
         printf( "%s", buf ) ;
      }
      fclose( fp ) ;
   }
}