/* Problem 17 */
	    #include <stdio.h>
	    #include <string.h>
	    class folder {
		char s[31];
		int pos;
		int len;
		int inc;
	      public:
		folder(char []);
		char next();
		void operator+=(folder);
		int size() { return len; }
	    };

	    folder::folder(char str[])
	    {
		strcpy(s, str);
		len = strlen(s);
		pos = 1; 
		inc = 2;
	    }

	    char folder::next()
	    {
		char c = s[pos];
		pos = pos + inc;
		if (pos >= len) {
		    inc = -2;
		    if (pos == len)
			pos--;
		    else
			pos = pos - 3;
		}
		else if (pos < 0) {
		    inc = 2;
		    pos = pos + 3;
		}
		return c;
	    }

	    void folder::operator+=(folder a)
	    {
		int i = 0;
		while (i < a.len) {
		    s[len] = a.s[i];
		    i++;
		    len++;
		}
		s[len] = '\0';
	    }

	    void operator!(folder a) // hint: this is no longer not!
	    {
		for (int i = 0; i < a.size(); i++)
		    printf("%c",  a.next());
	    }

	    int main()
	    {
		folder x("tgnee"), y("tb*");
		x += y;
		!x;
		printf("\n");
		return 0;
	    }