{"trustable":true,"prependHtml":"\u003cstyle type\u003d\"text/css\"\u003e\n h1 { font-size: 1.2em; }\n\u003c/style\u003e\n","sections":[{"title":"","value":{"format":"HTML","content":"\n\u003cdiv class\u003d\"md\"\u003e\u003cp\u003eGiven a tree of \u003cspan class\u003d\"math inline\"\u003e$ n $\u003c/span\u003e nodes, your task is to count the number of distinct paths that have at least \u003cspan class\u003d\"math inline\"\u003e$ k_1 $\u003c/span\u003e and at most \u003cspan class\u003d\"math inline\"\u003e$ k_2 $\u003c/span\u003e edges.\u003c/p\u003e\n\u003ch1 id\u003d\"input\"\u003eInput\u003c/h1\u003e\n\u003cp\u003eThe first input line contains three integers \u003cspan class\u003d\"math inline\"\u003e$ n $\u003c/span\u003e, \u003cspan class\u003d\"math inline\"\u003e$ k_1 $\u003c/span\u003e and \u003cspan class\u003d\"math inline\"\u003e$ k_2 $\u003c/span\u003e: the number of nodes and the path lengths. The nodes are numbered \u003cspan class\u003d\"math inline\"\u003e$ 1,2,\\ldots,n $\u003c/span\u003e.\u003c/p\u003e\n\u003cp\u003eThen there are \u003cspan class\u003d\"math inline\"\u003e$ n-1 $\u003c/span\u003e lines describing the edges. Each line contains two integers \u003cspan class\u003d\"math inline\"\u003e$ a $\u003c/span\u003e and \u003cspan class\u003d\"math inline\"\u003e$ b $\u003c/span\u003e: there is an edge between nodes \u003cspan class\u003d\"math inline\"\u003e$ a $\u003c/span\u003e and \u003cspan class\u003d\"math inline\"\u003e$ b $\u003c/span\u003e.\u003c/p\u003e\n\u003ch1 id\u003d\"output\"\u003eOutput\u003c/h1\u003e\n\u003cp\u003ePrint one integer: the number of paths.\u003c/p\u003e\n\u003ch1 id\u003d\"constraints\"\u003eConstraints\u003c/h1\u003e\n\u003cul\u003e\n\u003cli\u003e\u003cspan class\u003d\"math inline\"\u003e$ 1 \\le k_1 \\le k_2 \\le n \\le 2 \\cdot 10^5 $\u003c/span\u003e\u003c/li\u003e\n\u003cli\u003e\u003cspan class\u003d\"math inline\"\u003e$ 1 \\le a,b \\le n $\u003c/span\u003e\u003c/li\u003e\n\u003c/ul\u003e\n\u003ch1 id\u003d\"example\"\u003eExample\u003c/h1\u003e\n\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\u003e5 2 3\n1 2\n2 3\n3 4\n3 5\n\u003c/pre\u003e\u003c/td\u003e\n \u003ctd\u003e\u003cpre\u003e6\n\u003c/pre\u003e\u003c/td\u003e\n \u003c/tr\u003e\n\u003c/tbody\u003e\n\u003c/table\u003e\n\u003c/div\u003e "}}]}