{"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\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":"\u003cdiv\u003e\n zzh有一棵n个顶点的树。每个顶点要么被涂成了黑色,要么被涂成了白色。\n\u003c/div\u003e \n\u003cdiv\u003e\n \u0026nbsp;\n\u003c/div\u003e \n\u003cdiv\u003e \n \u003cspan\u003e\u003cspan\u003e我们考虑删掉k条边,那么这棵树就被分成(k\u003c/span\u003e\u003c/span\u003e +1)部分。同时,要求,每个部分是都存在黑色的点。\n\u003c/div\u003e \n\u003cdiv\u003e\n \u0026nbsp;\n\u003c/div\u003e \n\u003cdiv\u003e\n 现在,聪明的zzh想要知道,有多少种不同的分割方法,使得分割出来的每个部分恰好只有一个黑点。由于答案可能很大,请对(10^9+7)取模。\n\u003c/div\u003e"}},{"title":"Input","value":{"format":"HTML","content":"\u003cdiv\u003e \n \u003cspan\u003e\u003cspan\u003e第一行包含一个整数n(2≤n≤10\u003c/span\u003e\u003c/span\u003e^ \n \u003cspan\u003e\u003cspan\u003e5),表示树的顶点数量。\u003c/span\u003e\u003c/span\u003e\n\u003c/div\u003e \n\u003cdiv\u003e\n \u0026nbsp;\n\u003c/div\u003e \n\u003cdiv\u003e\n 第二行包含了树的描述,有个n-1个非负整数P0,P1,...,Pn-2(0≤PI≤i)。其中pi表示第(i + \n \u003cspan\u003e\u003cspan\u003e1)个点和顶点pi有边。树的顶点编号从0到n\u003c/span\u003e\u003c/span\u003e - \n \u003cspan\u003e1。\u003c/span\u003e\n\u003c/div\u003e \n\u003cdiv\u003e\n \u0026nbsp;\n\u003c/div\u003e \n\u003cdiv\u003e\n 第三行包含顶点的颜色的描述:n个整数X0,X1,...,Xn-1(xi为0或1)。如果xi为等于1,顶点i被着色成黑色。否则,顶点为白色。\n\u003c/div\u003e"}},{"title":"Output","value":{"format":"HTML","content":"\u003cp\u003e \u003cspan\u003e输出有多少种不同的分割方法。\u003c/span\u003e(\u003cspan\u003e注意取模)\u003c/span\u003e\u003c/p\u003e"}},{"title":"Sample Input","value":{"format":"HTML","content":"\u003cdiv\u003e \n \u003cdiv\u003e \n \u003cdiv\u003e \n \u003cspan\u003e输入样例1:\u003c/span\u003e\n \u003c/div\u003e \n \u003cdiv\u003e\n 3\n \u003c/div\u003e \n \u003cdiv\u003e\n 0 0\n \u003c/div\u003e \n \u003cdiv\u003e\n 0 1 1\n \u003c/div\u003e \n \u003cdiv\u003e\n \u0026nbsp;\n \u003c/div\u003e \n \u003cdiv\u003e \n \u003cspan\u003e输入样例2:\u003c/span\u003e\n \u003c/div\u003e \n \u003cdiv\u003e\n 6\n \u003c/div\u003e \n \u003cdiv\u003e\n 0 1 1 0 4\n \u003c/div\u003e \n \u003cdiv\u003e\n 1 1 0 0 1 0\n \u003c/div\u003e \n \u003cdiv\u003e\n \u0026nbsp;\n \u003c/div\u003e \n \u003cdiv\u003e \n \u003cspan\u003e输入样例3:\u003c/span\u003e\n \u003c/div\u003e \n \u003cdiv\u003e\n 10\n \u003c/div\u003e \n \u003cdiv\u003e\n 0 1 2 1 4 4 4 0 8\n \u003c/div\u003e \n \u003cdiv\u003e\n 0 0 0 1 0 1 1 0 0 1\n \u003c/div\u003e \n \u003c/div\u003e \n\u003c/div\u003e"}},{"title":"Sample Output","value":{"format":"HTML","content":"\u003cdiv\u003e \n \u003cspan\u003e输出样例1:\u003c/span\u003e\n\u003c/div\u003e \n\u003cdiv\u003e\n 2\n\u003c/div\u003e \n\u003cdiv\u003e\n \u0026nbsp;\n\u003c/div\u003e \n\u003cdiv\u003e \n \u003cspan\u003e输出样例2:\u003c/span\u003e\n\u003c/div\u003e \n\u003cdiv\u003e\n 1\n\u003c/div\u003e \n\u003cdiv\u003e\n \u0026nbsp;\n\u003c/div\u003e \n\u003cdiv\u003e \n \u003cspan\u003e输出样例3:\u003c/span\u003e\n\u003c/div\u003e \n\u003cdiv\u003e\n 27\n\u003c/div\u003e"}}]}