if (str == "next")
		{
			bool f = 1, f2 = 1;
			int j = 1, suc = 0;
			while (j != 0)
				if (v[j].k > x)
				{
					f2 = 0;
					suc = j;
					j = v[j].l;
				}
				else if (v[j].r == 0 && f2)
				{
					f = 0;
					cout << "none\n";
					break;
				}
				else
					j = v[j].r;
			if (f)
				cout << v[suc].k <<"\n";
		}

		if (str == "prev")
		{
			bool f = 1, f2 = 1;
			int j = 1, suc = 0;
			while (j != 0)
				if (v[j].k < x)
				{
					f2 = 0;
					suc = j;
					j = v[j].r;
				}
				else if (v[j].l == 0 && f2)
				{
					f = 0;
					cout << "none\n";
					break;
				}
				else
					j = v[j].l;
			if (f)
				cout << v[suc].k << "\n";
		}