# Knuth's arrow

define f(l, x, y) {
	if (l <= 0) {
		return x + y;
	}
	if (l == 1) {
		return x * y;
	}
	if (l == 2) {
		return x ^ y;
	} else {
		if (y <= 1) {
			return x;
		} else {
			return f(l - 1, x, f(l, x, y - 1));
		}
	}
}

define k(l, x, y) { # Knuth ¤ÎÌð°õ
	return f(l + 1, x, y)
}

define f0(x, y) { # ²Ã»»
	return x + y;
	if (y <= 0) {
		return x;
	} else {
		return 1 + f0(x, y - 1);
	}
}

define f1(x, y) { # ¾è»»
	if (y <= 1) {
		return x;
	} else {
		return f0(x, f1(x, y - 1));
	}
}

define f2(x, y) { # »Ø¿ô´Ø¿ô (x ^ y)
	if (y <= 1) {
		return x;
	} else {
		return f1(x, f2(x, y - 1));
	}
}

define f3(x, y) { # x ^^ y
	if (y <= 1) {
		return x;
	} else {
		return f2(x, f3(x, y - 1));
	}
}