#include    <stdio.h>
#include    <stdlib.h>
#include    <math.h>
#include    "project.h"

/********************************************************
 *	Outputs the paper-folding sequence		*
 *	Using the folding instructions given.		*
 *	David Longbottom				*
 ********************************************************/


int main (int argc, char *argv[]) {
	int	*instr;
	int	i, n=0, max;
	char	c;
	int	allocated = 15;
	int	order, j, b;

	//read in folding instructions
	instr = (int *)malloc(allocated*sizeof(int));
	while ((c = getchar()) != '\n' && c != EOF) {
		instr[n] = c;
		n++;
		if(n >= allocated) {
			allocated *=2;
			instr = (int *)realloc(instr,allocated*sizeof(int));
		}
	}

	max = (int)pow(2,n) - 1;
	fprintf(stderr,"%i folds gives %i creases.\n",n,max);

	//now generate sequence
	//see automaton
	for (i = 1 ; i <= max ; i++) {
		order = 0;
		j = i;				//start
		b = 2;
		while(b == 2) {
			if ( !(j % 2) ) {	//is j even?
				j = j / 2;
				order++;
			} else {
				b = ((j-1) / 2) % 2;	//b = 0 or 1
			}
		}

		b = (instr[order] == A ? b : 1-b );	//invert b if its instruction was so
		putchar( b == 0 ? A : B);
	
	}

	putchar('\n');

	return(EXIT_SUCCESS);

}