{"trustable":false,"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\n\u003cscript\u003e\n window.katexOptions \u003d {\n delimiters: [\n {left: \u0027$$$$$$\u0027, right: \u0027$$$$$$\u0027, display: true},\n {left: \u0027$$$\u0027, right: \u0027$$$\u0027, display: false},\n {left: \u0027$$\u0027, right: \u0027$$\u0027, display: true},\n {left: \u0027$\u0027, right: \u0027$\u0027, display: false}\n ]\n };\n\u003c/script\u003e\n","sections":[{"title":"","value":{"format":"MD","content":"\u003cp\u003eGiáo sư X đang trồng cây trong vườn của ông ấy\u003c/p\u003e\n\u003cp\u003eCó\u003cspan class\u003d\"tex-span\"\u003e\u003ci\u003en\u003c/i\u003e\u003c/span\u003e n đỉnh trên cây. Mỗi cây được sơn màu đen hoặc trắng. Giáo sư X không thích nhiều màu vì nhìn rất nhức mắt, vì vậy anh ấy định sơn các cây về cùng màu đen hoặc trắng.\u003c/p\u003e\n\u003cp\u003eGiáo sư X sẽ sử dụng phép tô màu \u003cspan class\u003d\"tex-span\"\u003e\u003ci\u003epaint\u003c/i\u003e(\u003ci\u003ev\u003c/i\u003e)\u003c/span\u003e, trong đó \u003cspan class\u003d\"tex-span\"\u003e\u003ci\u003ev\u003c/i\u003e\u003c/span\u003e là một đỉnh trên cây. Phép tô màu này thay đổi màu sắc của tất cả các đỉnh \u003cspan class\u003d\"tex-span\"\u003e\u003ci\u003eu\u003c/i\u003e\u003c/span\u003e sao cho đường đi ngắn nhất từ \u003cspan class\u003d\"tex-span\"\u003e\u003ci\u003ev\u003c/i\u003e\u003c/span\u003e tới \u003cspan class\u003d\"tex-span\"\u003e\u003ci\u003eu\u003c/i\u003e\u003c/span\u003e có cùng màu (bao gồm cả \u003cspan class\u003d\"tex-span\"\u003e\u003ci\u003ev\u003c/i\u003e\u003c/span\u003e và \u003cspan class\u003d\"tex-span\"\u003e\u003ci\u003eu\u003c/i\u003e\u003c/span\u003e). Ví dụ:\n\u003c/p\u003e\n\u003ccenter\u003e \n \u003cimg class\u003d\"tex-graphics\" src\u003d\"CDN_BASE_URL/8e4c5b941260111688903047dd1add0b?v\u003d1635306481\" style\u003d\"max-width: 100.0%;max-height: 100.0%;\"\u003e \n\u003c/center\u003e\n\u003cp\u003evà áp dụng phép tô màu \u003cspan class\u003d\"tex-span\"\u003e\u003ci\u003epaint\u003c/i\u003e(3)\u003c/span\u003e:\u003c/p\u003e\n\u003ccenter\u003e \n \u003cimg class\u003d\"tex-graphics\" src\u003d\"CDN_BASE_URL/a035352d5d9d2b2ca6c50e9997757d9b?v\u003d1635306481\" style\u003d\"max-width: 100.0%;max-height: 100.0%;\"\u003e \n\u003c/center\u003e\n\u003cp\u003eGiáo sư X muốn tính xem số phép tô màu ít nhất cần sử dụng là bao nhiêu. Bạn hãy giúp giáo sư nhé\u003c/p\u003e"}},{"title":"Input","value":{"format":"MD","content":"\u003cp\u003eDòng đầu tiên chứa số nguyên dương \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 ≤ 200 000\u003c/span\u003e)\u0026nbsp;— số lượng đỉnh của cây.\u003c/p\u003e\n\u003cp\u003eDòng thứ hai chứa \u003cspan class\u003d\"tex-span\"\u003e\u003ci\u003en\u003c/i\u003e\u003c/span\u003e số nguyên \u003cspan class\u003d\"tex-span\"\u003e\u003ci\u003ecolor\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\"\u003e0 ≤ \u003ci\u003ecolor\u003c/i\u003e\u003csub class\u003d\"lower-index\"\u003e\u003ci\u003ei\u003c/i\u003e\u003c/sub\u003e ≤ 1\u003c/span\u003e)\u0026nbsp;— màu của đỉnh $i$. \u003cspan class\u003d\"tex-span\"\u003e\u003ci\u003ecolor\u003c/i\u003e\u003csub class\u003d\"lower-index\"\u003e\u003ci\u003ei\u003c/i\u003e\u003c/sub\u003e \u003d 0\u003c/span\u003e có nghĩa rằng đỉnh thứ $i$ được tô màu trắng, ngược lại, \u003cspan class\u003d\"tex-span\"\u003e\u003ci\u003ecolor\u003c/i\u003e\u003csub class\u003d\"lower-index\"\u003e\u003ci\u003ei\u003c/i\u003e\u003c/sub\u003e \u003d 1\u003c/span\u003e có nghĩa rằng đỉnh thứ $i$ được tô màu đen.\u003c/p\u003e\n\u003cp\u003e\u003cspan class\u003d\"tex-span\"\u003e\u003ci\u003en\u003c/i\u003e - 1\u003c/span\u003e dòng tiếp theo, mỗi dòng chứa hai số nguyên \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 và \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, \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)\u0026nbsp; đại diện cho các cạnh trên cây. Dữ liệu đảm bảo rằng $n-1$ cạnh này tạo thành một cây $n$ đỉnh."}},{"title":"Output","value":{"format":"MD","content":"Đưa ra một số nguyên duy nhất là kết quả bài toán."}},{"title":"Examples","value":{"format":"MD","content":"\u003cdiv class\u003d\"sample-test\"\u003e\n \u003cdiv class\u003d\"input\"\u003e\n \u003cdiv class\u003d\"title\"\u003e\n Input\n \u003c/div\u003e\n \u003cpre\u003e11\u003cbr\u003e0 0 0 1 1 0 1 0 0 1 1\u003cbr\u003e1 2\u003cbr\u003e1 3\u003cbr\u003e5 6\u003cbr\u003e5 7\u003cbr\u003e3 8\u003cbr\u003e3 9\u003cbr\u003e3 10\u003cbr\u003e4 2\u003cbr\u003e5 2\u003cbr\u003e9 11\u003cbr\u003e\u003c/pre\u003e\n \u003c/div\u003e\n \u003cdiv class\u003d\"output\"\u003e\n \u003cdiv class\u003d\"title\"\u003e\n Output\n \u003c/div\u003e\n \u003cpre\u003e2\u003cbr\u003e\u003c/pre\u003e\n \u003c/div\u003e\n\u003c/div\u003e"}}]}