#include <stdio.h>
#include <string.h>
#include <unistd.h>

int find_new_index(char *pattern, int index, int newstart);

int main(int argc, char **argv)
{
	int index=0, patlen, replen;
	int symbol;
	char *pattern, *replacement;
	if ( argc < 2 ) {
		printf("Usage: %s pattern replacement\n", argv[0]);
		return 1;
	}
	pattern=argv[1];
	replacement=argv[2];
	patlen=strlen(pattern);
	replen=strlen(replacement);

	while ( (symbol=getchar()) != EOF ) {

		if ( index == patlen) {
			write(fileno(stdout), replacement, replen);
			index = 0;
		}

restart:
		if ( symbol == pattern[index] ) {
			index++;
		} else {
			if ( index ) {
				int to_print = find_new_index(pattern, index, 1);
				write(fileno(stdout), pattern, to_print);
				index -= to_print;
				goto restart;
			} else {
				write(fileno(stdout), &symbol, 1); // XXX - won't work on bigendian
			}
		}
	}
	write(fileno(stdout), pattern, index);

	return 0;
}

int find_new_index(char *pattern, int index, int newstart)
{
	int i;
	for ( i = 0; i+newstart < index ; i++) {
		if ( pattern[newstart+i] != pattern[i] ) {
			return i + find_new_index(pattern, index, newstart+1);
		}
	}
	return newstart;
}