{"trustable":true,"prependHtml":"\u003cstyle type\u003d\"text/css\"\u003e\n #problem-body \u003e pre {\n display: block;\n padding: 9.5px;\n margin: 0 0 10px;\n font-size: 13px;\n line-height: 1.42857143;\n word-break: break-all;\n word-wrap: break-word;\n color: #333;\n background: rgba(255, 255, 255, 0.5);\n border: 1px solid #ccc;\n border-radius: 6px;\n }\n\u003c/style\u003e\n","sections":[{"title":"","value":{"format":"HTML","content":"\u003cdiv id\u003d\"problem-body\"\u003e\n\t\u003cp\u003eYou are given a tree (an acyclic undirected connected graph) with N nodes, and nodes numbered 1,2,3...,N. Each edge has an integer value assigned to it(note that the value can be negative). Each node has a color, white or black.\r\nWe define dist(a, b) as the sum of the value of the edges on the path from node a to node b.\r\n\u003c/p\u003e\r\n\u003cp\u003e\r\nAll the nodes are white initially.\r\n\u003c/p\u003e\r\n\u003cp\u003e\r\nWe will ask you to perform some instructions of the following form:\r\n\u003c/p\u003e\r\n\r\n\u003cul\u003e\r\n\u003cli\u003e\u003cb\u003eC a\u003c/b\u003e : change the color of node a.(from black to white or from white to black)\u003cbr\u003e\r\n\u003c/li\u003e\u003cli\u003e\u003cb\u003eA\u003c/b\u003e : ask for the maximum dist(a, b), both of node a and node b must be white(a can be equal to b). Obviously, as long as there is a white node, the result will always be non negative. \r\n\u003c/li\u003e\u003c/ul\u003e\r\n\r\n\u003ch3\u003eInput\u003c/h3\u003e\r\n\u003cul\u003e\r\n\u003cli\u003eIn the first line there is an integer N (N \u0026lt;\u003d 100000)\r\n\u003c/li\u003e\u003cli\u003eIn the next N-1 lines, the i-th line describes the i-th edge: a line with three integers a b c denotes an edge between a, b of value c (-1000 \u0026lt;\u003d c \u0026lt;\u003d 1000)\r\n\u003c/li\u003e\u003cli\u003eIn the next line, there is an integer Q denotes the number of instructions (Q \u0026lt;\u003d 100000)\r\n\u003c/li\u003e\u003cli\u003eIn the next Q lines, each line contains an instruction \"C a\" or \"A\"\r\n\u003c/li\u003e\u003c/ul\u003e\r\n\r\n\u003ch3\u003eOutput\u003c/h3\u003e\r\n\u003cp\u003eFor each \"A\" operation, write one integer representing its result.\r\nIf there is no white node in the tree, you should write \"They have disappeared.\".\r\n\u003c/p\u003e\r\n\r\n\u003ch3\u003eExample\u003c/h3\u003e\r\n\r\n\u003cdiv\u003e\u003ctable class\u003d\"vjudge_sample\"\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\n1 2 1\r\n1 3 1\r\n7\r\nA\r\nC 1\r\nA\r\nC 2\r\nA\r\nC 3\r\nA\r\n\r\n\u003c/pre\u003e\u003c/td\u003e\n \u003ctd\u003e\u003cpre\u003e2\r\n2\r\n0\r\nThey have disappeared.\u003c/pre\u003e\u003c/td\u003e\n \u003c/tr\u003e\n\u003c/tbody\u003e\n\u003c/table\u003e\n\u003c/div\u003e\r\n\r\n\n\u003c/div\u003e"}}]}