{"trustable":true,"prependHtml":"\u003cstyle type\u003d\u0027text/css\u0027\u003e\n .input, .output {\n border: 1px solid #888888;\n }\n .output {\n margin-bottom: 1em;\n position: relative;\n top: -1px;\n }\n .output pre, .input pre {\n background-color: #EFEFEF;\n line-height: 1.25em;\n margin: 0;\n padding: 0.25em;\n }\n \u003c/style\u003e\n \u003clink rel\u003d\"stylesheet\" href\u003d\"//codeforces.org/s/96598/css/problem-statement.css\" type\u003d\"text/css\" /\u003e\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 type\u003d\"text/javascript\" async src\u003d\"https://mathjax.codeforces.org/MathJax.js?config\u003dTeX-AMS_HTML-full\"\u003e\u003c/script\u003e","sections":[{"title":"","value":{"format":"HTML","content":"\u003cp\u003eExistem \u003cspan class\u003d\"tex-span\"\u003e\u003ci\u003en\u003c/i\u003e\u003c/span\u003e cidades e \u003cspan class\u003d\"tex-span\"\u003e\u003ci\u003en\u003c/i\u003e - 1\u003c/span\u003e estradas nos Sete Reinos, cada estrada conecta duas cidades e podemos chegar a qualquer cidade a partir de qualquer outra pelas estradas.\u003c/p\u003e\u003cp\u003eTheon e Yara Greyjoy estão em um cavalo na primeira cidade, eles estão começando a viajar pelas estradas. Mas o tempo está nebuloso, então eles não conseguem ver para onde o cavalo os leva. Quando o cavalo chega a uma cidade (incluindo a primeira), ele vai para uma das cidades conectadas à cidade atual. Mas é um cavalo estranho, ele só vai para cidades onde eles não estiveram antes. Em cada cidade assim, o cavalo vai com probabilidades iguais e para quando não há mais cidades assim.\u003c/p\u003e\u003cp\u003eDeixe o comprimento de cada estrada ser \u003cspan class\u003d\"tex-span\"\u003e1\u003c/span\u003e. A jornada começa na cidade \u003cspan class\u003d\"tex-span\"\u003e1\u003c/span\u003e. Qual é o comprimento esperado (valor esperado do comprimento) da jornada deles? Você pode ler sobre valor esperado (média) pelo link \u003ca href\u003d\"https://pt.wikipedia.org/wiki/Valor_esperado\"\u003ehttps://pt.wikipedia.org/wiki/Valor_esperado\u003c/a\u003e.\u003c/p\u003e"}},{"title":"Entrada","value":{"format":"HTML","content":"\u003cp\u003eA primeira linha contém um único inteiro \u003cspan class\u003d\"tex-span\"\u003e\u003ci\u003en\u003c/i\u003e\u003c/span\u003e (\u003cspan class\u003d\"tex-span\"\u003e1 ≤ \u003ci\u003en\u003c/i\u003e ≤ 100000\u003c/span\u003e) - número de cidades.\u003c/p\u003e\u003cp\u003eEntão seguem \u003cspan class\u003d\"tex-span\"\u003e\u003ci\u003en\u003c/i\u003e - 1\u003c/span\u003e linhas. A \u003cspan class\u003d\"tex-span\"\u003e\u003ci\u003ei\u003c/i\u003e\u003c/span\u003e-ésima linha dessas linhas contém dois inteiros \u003cspan class\u003d\"tex-span\"\u003e\u003ci\u003eu\u003c/i\u003e\u003csub class\u003d\"lower-index\"\u003e\u003ci\u003ei\u003c/i\u003e\u003c/sub\u003e\u003c/span\u003e e \u003cspan class\u003d\"tex-span\"\u003e\u003ci\u003ev\u003c/i\u003e\u003csub class\u003d\"lower-index\"\u003e\u003ci\u003ei\u003c/i\u003e\u003c/sub\u003e\u003c/span\u003e (\u003cspan class\u003d\"tex-span\"\u003e1 ≤ \u003ci\u003eu\u003c/i\u003e\u003csub class\u003d\"lower-index\"\u003e\u003ci\u003ei\u003c/i\u003e\u003c/sub\u003e, \u003ci\u003ev\u003c/i\u003e\u003csub class\u003d\"lower-index\"\u003e\u003ci\u003ei\u003c/i\u003e\u003c/sub\u003e ≤ \u003ci\u003en\u003c/i\u003e\u003c/span\u003e, \u003cspan class\u003d\"tex-span\"\u003e\u003ci\u003eu\u003c/i\u003e\u003csub class\u003d\"lower-index\"\u003e\u003ci\u003ei\u003c/i\u003e\u003c/sub\u003e ≠ \u003ci\u003ev\u003c/i\u003e\u003csub class\u003d\"lower-index\"\u003e\u003ci\u003ei\u003c/i\u003e\u003c/sub\u003e\u003c/span\u003e) - as cidades conectadas pela \u003cspan class\u003d\"tex-span\"\u003e\u003ci\u003ei\u003c/i\u003e\u003c/span\u003e-ésima estrada.\u003c/p\u003e\u003cp\u003eÉ garantido que é possível chegar a qualquer cidade a partir de qualquer outra pelas estradas.\u003c/p\u003e"}},{"title":"Saída","value":{"format":"HTML","content":"\u003cp\u003eImprima um número - o comprimento esperado da jornada deles. A jornada começa na cidade \u003cspan class\u003d\"tex-span\"\u003e1\u003c/span\u003e.\u003c/p\u003e\u003cp\u003eSua resposta será considerada correta se o erro absoluto ou relativo não exceder \u003cspan class\u003d\"tex-span\"\u003e10\u003csup class\u003d\"upper-index\"\u003e - 6\u003c/sup\u003e\u003c/span\u003e.\u003c/p\u003e\u003cp\u003eOu seja: vamos assumir que sua resposta seja \u003cspan class\u003d\"tex-span\"\u003e\u003ci\u003ea\u003c/i\u003e\u003c/span\u003e, e a resposta do júri seja \u003cspan class\u003d\"tex-span\"\u003e\u003ci\u003eb\u003c/i\u003e\u003c/span\u003e. O programa verificador considerará sua resposta correta se \u003cimg align\u003d\"middle\" class\u003d\"tex-formula\" src\u003d\"CDN_BASE_URL/497ae581fcd97e6c60a28891d1267ebe?v\u003d1710252078\" style\u003d\"max-width: 100.0%;max-height: 100.0%;\"\u003e.\u003c/p\u003e"}},{"title":"Exemplo 1","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\u003e4\n1 2\n1 3\n2 4\n\u003c/pre\u003e\u003c/td\u003e\n \u003ctd\u003e\u003cpre\u003e1.500000000000000\n\u003c/pre\u003e\u003c/td\u003e\n \u003c/tr\u003e\n\u003c/tbody\u003e\n\u003c/table\u003e"}},{"title":"Exemplo 2","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\u003e5\n1 2\n1 3\n3 4\n2 5\n\u003c/pre\u003e\u003c/td\u003e\n \u003ctd\u003e\u003cpre\u003e2.000000000000000\n\u003c/pre\u003e\u003c/td\u003e\n \u003c/tr\u003e\n\u003c/tbody\u003e\n\u003c/table\u003e"}},{"title":"Nota","value":{"format":"HTML","content":"\u003cp\u003eNo primeiro exemplo, a jornada deles pode terminar nas cidades \u003cspan class\u003d\"tex-span\"\u003e3\u003c/span\u003e ou \u003cspan class\u003d\"tex-span\"\u003e4\u003c/span\u003e com igual probabilidade. A distância até a cidade \u003cspan class\u003d\"tex-span\"\u003e3\u003c/span\u003e é \u003cspan class\u003d\"tex-span\"\u003e1\u003c/span\u003e e até a cidade \u003cspan class\u003d\"tex-span\"\u003e4\u003c/span\u003e é \u003cspan class\u003d\"tex-span\"\u003e2\u003c/span\u003e, então o comprimento esperado é \u003cspan class\u003d\"tex-span\"\u003e1.5\u003c/span\u003e.\u003c/p\u003e\u003cp\u003eNo segundo exemplo, a jornada deles pode terminar na cidade \u003cspan class\u003d\"tex-span\"\u003e4\u003c/span\u003e ou \u003cspan class\u003d\"tex-span\"\u003e5\u003c/span\u003e. A distância até ambas as cidades é \u003cspan class\u003d\"tex-span\"\u003e2\u003c/span\u003e, então o comprimento esperado é \u003cspan class\u003d\"tex-span\"\u003e2\u003c/span\u003e.\u003c/p\u003e"}}]}