{"trustable":true,"sections":[{"title":"","value":{"format":"HTML","content":"\u003cdiv class\u003d\"problem_par\"\u003e\u003cdiv class\u003d\"problem_par_normal\"\u003eVasya’s dad is good in maths. Lately his favorite objects have been \"beautiful\" directed graphs.\r\nDad calls a graph \"beautiful\" if all the following conditions are true:\r\n\u003col\u003e\r\n\u003cli\u003eThe graph contains exactly \u003ci\u003eN\u003c/i\u003e vertices and \u003ci\u003eN\u003c/i\u003e−1 edges.\u003c/li\u003e\r\n\u003cli\u003eExactly one vertex has no entering edges.\u003c/li\u003e\r\n\u003cli\u003eThe graph contains no directed cycles.\u003c/li\u003e\r\n\u003c/ol\u003e\r\nDad calls two \"beautiful\" graphs isomorphic, if the vertices of the first graph can be renumbered in such way that it turns into the second one.\u003c/div\u003e\u003c/div\u003e\u003cdiv class\u003d\"problem_par\"\u003e\u003cdiv class\u003d\"problem_par_normal\"\u003eDad picks an integer \u003ci\u003eN\u003c/i\u003e, stocks up blank paper, and draws a \"beautiful\" graph on each sheet. He verifies that no two drawn graphs are isomorphic.\u003c/div\u003e\u003c/div\u003e\u003cdiv class\u003d\"problem_par\"\u003e\u003cdiv class\u003d\"problem_par_normal\"\u003eGiven the number \u003ci\u003eN\u003c/i\u003e, you are to find the number of sheets that Vasya\u0027s dad has to stock up.\u003c/div\u003e\u003c/div\u003e"}},{"title":"Input","value":{"format":"HTML","content":"\u003cdiv class\u003d\"problem_par\"\u003e\u003cdiv class\u003d\"problem_par_normal\"\u003eInput contains the single integer \u003ci\u003eN\u003c/i\u003e (1 ≤ \u003ci\u003eN\u003c/i\u003e ≤ 50).\u003c/div\u003e\u003c/div\u003e"}},{"title":"Output","value":{"format":"HTML","content":"\u003cdiv class\u003d\"problem_par\"\u003e\u003cdiv class\u003d\"problem_par_normal\"\u003eOutput the number of \"beautiful\" graphs with \u003ci\u003eN\u003c/i\u003e vertices.\u003c/div\u003e\u003c/div\u003e"}},{"title":"Sample","value":{"format":"HTML","content":"\u003ctable class\u003d\u0027vjudge_sample\u0027\u003e\n\u003cthead\u003e\n \u003ctr\u003e\n \u003cth\u003eInput\u003c/th\u003e\n \u003cth\u003eOutput\u003c/th\u003e\n \u003c/tr\u003e\n\u003c/thead\u003e\n\u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd\u003e\u003cpre\u003e3\r\n\u003c/pre\u003e\u003c/td\u003e\n \u003ctd\u003e\u003cpre\u003e2\r\n\u003c/pre\u003e\u003c/td\u003e\n \u003c/tr\u003e\n\u003c/tbody\u003e\n\u003c/table\u003e\n\u003cbr\u003e\u003ctable class\u003d\u0027vjudge_sample\u0027\u003e\n\u003cthead\u003e\n \u003ctr\u003e\n \u003cth\u003eInput\u003c/th\u003e\n \u003cth\u003eOutput\u003c/th\u003e\n \u003c/tr\u003e\n\u003c/thead\u003e\n\u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd\u003e\u003cpre\u003e5\r\n\u003c/pre\u003e\u003c/td\u003e\n \u003ctd\u003e\u003cpre\u003e9\r\n\u003c/pre\u003e\u003c/td\u003e\n \u003c/tr\u003e\n\u003c/tbody\u003e\n\u003c/table\u003e\n"}}]}