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

void printback();

char *buffer;

const int range = 'a'+26;
int length = 0;
int spin(register char* p)
{
	for (*p='a';*p<range;*p+=1)
    {
        if (p < buffer+length)
		{
            spin(p+1);
		}
		printf(" %s\n",buffer);
    }
	(*p)--; //fixes special case parent foobar
    return 1;
}

/*
 * ./recurse <num_chars>
 */
int main(int argc, char ** argv)
{
    int i;
    if (argc!=2) return argc;

    int pass_length = atoi(argv[1]);

    buffer = (char *) calloc(pass_length+1,sizeof(char));
    buffer[pass_length]='\0';
    
    /* This is a call to a recursive function */
	for(i=0;i<=pass_length-1;i++){
    	memset(buffer,'\0',pass_length);
		length = i;
		spin(buffer);
	}

    return 0;
}