use t3x: t;
use string: str;
use io;

yesno() do var b::10;
	while (%1) do
		io.readln(b, 10);
		if (b::0 = 'y') return %1;
		if (b::0 = 'n') return 0;
	end
end

do var n, d;
	io.nl();
	io.writeln("Think of a number between 0 and 1023.");
	n := 0;
	d := 512;
	while (d) do
		io.writes("Is your number greater than ");
		io.writes(str.ntoa(n+d-1, 10));
		io.writes("? (y/n) ");
		if (yesno()) n := n + d;
		d := d / 2;
	end
	io.writes("Your number is ");
	io.writeln(str.ntoa(n, 10));
	io.nl();
end