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

int main(int argc, char * argv[]) {
	long snr;
	char * ptr;
	int i;

	if (argc != 2) {
		fprintf(stderr, "Usage: %s <serialnumber>\n", argv[0]);
		return -1;
	}
	
	snr = strtol(argv[1], &ptr, 16);
	if (ptr != argv[1] + strlen(argv[1])) {
		fprintf(stderr, "Illegal argument");
		return -1;
	}
	
	for (i = 0; i < 4; ++i) {
		unsigned char x = snr >> (i << 3);
		fputc(x, stdout);
	}
	fflush(stdout);

	return 0;
}