{"trustable":false,"prependHtml":"\u003cscript\u003e window.katexOptions \u003d { disable: true }; \u003c/script\u003e\n\u003cscript type\u003d\"text/x-mathjax-config\"\u003e\n MathJax.Hub.Config({\n tex2jax: {\n inlineMath: [[\u0027$$$\u0027,\u0027$$$\u0027], [\u0027$\u0027,\u0027$\u0027]],\n displayMath: [[\u0027$$$$$$\u0027,\u0027$$$$$$\u0027], [\u0027$$\u0027,\u0027$$\u0027]]\n }\n });\n\u003c/script\u003e\n\u003cscript async src\u003d\"https://mathjax.codeforces.org/MathJax.js?config\u003dTeX-AMS-MML_HTMLorMML\" type\u003d\"text/javascript\"\u003e\u003c/script\u003e","sections":[{"title":"","value":{"format":"HTML","content":"给定一张树图,你可以往图中的节点上放士兵\n\u003cbr\u003e\n每个士兵可以观察与其所在节点相邻的所有边\n\u003cbr\u003e\n问最少需要放多少士兵,使得整张图所有边都能被观察到\n\u003cbr\u003e\n----------\n\u003cbr\u003e\n\n\u003cscript type\u003d\u0027text/x-mathjax-config\u0027\u003eMathJax.Hub.Config({tex2jax: { inlineMath: [[\u0027$\u0027,\u0027$\u0027]] } }); \u003c/script\u003e\n\u003cscript type\u003d\u0027text/javascript\u0027 src\u003d\u0027https://cdnjs.cloudflare.com/ajax/libs/mathjax/2.7.1/MathJax.js?config\u003dTeX-AMS-MML_HTMLorMML\u0027\u003e\u003c/script\u003e\n\u003cscript type\u003d\u0027text/javascript\u0027\u003esetTimeout(function(){MathJax.Hub.Queue([\u0027Typeset\u0027, MathJax.Hub, \u0027left_view\u0027]);}, 2000);\u003c/script\u003e\n\u003cdiv class\u003d\"panel_content\"\u003e\n Bob enjoys playing computer games, especially strategic games, but sometimes he cannot find the solution fast enough and then he is very sad. Now he has the following problem. He must defend a medieval city, the roads of which form a tree. He has to put the minimum number of soldiers on the nodes so that they can observe all the edges. Can you help him?\n \u003cbr\u003e\n \u003cbr\u003eYour program should find the minimum number of soldiers that Bob has to put for a given tree.\n \u003cbr\u003e\n \u003cbr\u003eThe input file contains several data sets in text format. Each data set represents a tree with the following description:\n \u003cbr\u003e\n \u003cbr\u003ethe number of nodes\n \u003cbr\u003ethe description of each node in the following format\n \u003cbr\u003enode_identifier:(number_of_roads) node_identifier1 node_identifier2 ... node_identifier\n \u003cbr\u003eor\n \u003cbr\u003enode_identifier:(0)\n \u003cbr\u003e\n \u003cbr\u003eThe node identifiers are integer numbers between 0 and n-1, for n nodes (0 \u0026lt; n \u0026lt;\u003d 1500). Every edge appears only once in the input data.\n \u003cbr\u003e\n \u003cbr\u003eFor example for the tree: \n \u003cbr\u003e\n \u003cbr\u003e\n \u003cimg style\u003d\"max-width:100%;\" src\u003d\"CDN_BASE_URL/4da63a346da9449b383b34064f32eec8?v\u003d1626890220\"\u003e \n \u003cbr\u003e\n \u003cbr\u003ethe solution is one soldier ( at the node 1).\n \u003cbr\u003e\n \u003cbr\u003eThe output should be printed on the standard output. For each given input data set, print one integer number in a single line that gives the result (the minimum number of soldiers). An example is given in the following table:\n \u003cbr\u003e\n\u003c/div\u003e"}},{"title":"Input","value":{"format":"HTML","content":"\u003cpre\u003e4\n0:(1) 1\n1:(2) 2 3\n2:(0)\n3:(0)\n5\n3:(3) 1 4 2\n1:(1) 0\n2:(0)\n0:(0)\n4:(0)\u003c/pre\u003e"}},{"title":"Output","value":{"format":"HTML","content":"\u003cpre\u003e1\n2\u003c/pre\u003e"}},{"title":"Sample Input","value":{"format":"HTML","content":"\u003cpre\u003e4\n0:(1) 1\n1:(2) 2 3\n2:(0)\n3:(0)\n5\n3:(3) 1 4 2\n1:(1) 0\n2:(0)\n0:(0)\n4:(0)\u003c/pre\u003e"}},{"title":"Sample Output","value":{"format":"HTML","content":"\u003cpre\u003e1\n2\u003c/pre\u003e"}}]}