$$U_{356}(x, y) = \frac{y}{2} - \frac{\sqrt{4 x + \left(y + 1\right)^{2}}}{2} + \frac{1}{2}$$

$$T_{356}(n, m, k) = \begin{cases}0&\text{if n<k} ,\ \\- \frac{k {\binom{m + n}{m}} {\binom{k - n - 1}{m + n - 1}}}{m + n} \end{cases} $$