#include <stdio.h> /* fprintf(3), getc(3), putc(3), stderr, stdin, stdout */
#include <stdlib.h> /* exit(3) */
#include <sysexits.h> /* EX_OK, EX_USAGE, EX_SOFTWARE */
#include <unistd.h> /* getopt(3) */

/* Enable Unicode support using official Unicode library. */
#ifdef    USE_ICU
#	include <unicode/uchar.h>
	/* UCHAR_MAX_VALUE, u_tolower(3), u_toupper(3) */
#	include <unicode/umachine.h> /* UChar32 */
#	include <unicode/ustdio.h> /* u_fgetc(3) */
#else
#	include <ctype.h> /* tolower(3), toupper(3) */
#endif /* USE_ICU */

#define ASCII_MAX_VALUE 0x7F

int main(int argc, char *argv[]){
#ifdef USE_ICU
	UChar32
#else
	int
#endif
		c; /* iterating over character stream */

	if(argc > 1){
		fprintf(stderr, "Usage: %s\n", argv[0]);
		return EX_USAGE;
	}


#ifdef USE_ICU
	while((c = u_fgetc(stdin)) != U_EOF){
		if(c <= UCHAR_MAX_VALUE && c >= 0)
#	ifdef LOWERCASE
			c = u_tolower(c);
#	else
			c = u_toupper(c);
#	endif /* ifdef LOWERCASE */
		u_fputc(c, stdout);
#else
	while((c = getc(stdin)) != EOF){
		if(c <= ASCII_MAX_VALUE && c >= 0)
#	ifdef LOWERCASE
			c = tolower(c);
#	else
			c = toupper(c);
#	endif /* ifdef LOWERCASE */
		putc(c, stdout);
#endif /* ifdef USE_ICU */
	}
	return EX_OK;
}