{"raw_statement":[{"iden":"statement","content":"Prof. Du and Prof. Pang plan to build a sky garden near the city of Allin. In the garden, there will be a plant maze consisting of straight and circular roads.\n\nOn the blueprint of the plant maze, Prof. Du draws $n$ circles indicating the circular roads. All of them have center $(0, 0)$. The radius of the $i$-th circle is $i$.\n\nMeanwhile, Prof. Pang draws $m$ lines on the blueprint indicating the straight roads. All of the lines pass through $(0, 0)$. Each circle is divided into $2m$ parts with equal lengths by these lines.\n\nLet $Q$ be the set of the $n+m$ roads. Let $P$ be the set of all intersections of two different roads in $Q$. Note that each circular road and each straight road have two intersections.\n\nFor two different points $a\\in P$ and $b\\in P$, we define $dis(\\{a, b\\})$ to be the shortest distance one needs to walk from $a$ to $b$ along the roads. Please calculate the sum of $dis(\\{a, b\\})$ for all $\\{a, b\\}\\subseteq P$. "},{"iden":"input","content":"The only line contains two integers $n,m~(1\\le n,m\\le 500)$."},{"iden":"output","content":"Output one number -- the sum of the distances between every pair of points in $P$.\n\nYour answer is considered correct if its absolute or relative error does not exceed $10^{-6}$."},{"iden":"note","content":"![](https://cdn.luogu.com.cn/upload/image_hosting/81sxvtcp.png)\n\n$dis(p_1, p_2)=dis(p_2, p_3)=dis(p_3, p_4)=dis(p_1, p_4)=\\frac{\\pi}{2}$\n\n$dis(p_1, p_5)=dis(p_2, p_5)=dis(p_3, p_5)=dis(p_4, p_5)=1$\n\n$dis(p_1, p_3)=dis(p_2, p_4)=2$"}],"translated_statement":null,"sample_group":[["1 2","14.2831853072"],["2 3","175.4159265359"]],"show_order":[],"formal_statement":null,"simple_statement":null,"has_page_source":false}