{"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$$\u0027]]\n }\n });\n\u003c/script\u003e\n\u003cscript type\u003d\"text/javascript\" async src\u003d\"https://mathjax.codeforces.org/MathJax.js?config\u003dTeX-AMS_HTML-full\"\u003e\u003c/script\u003e","sections":[{"title":"","value":{"format":"HTML","content":"\u003cstyle type\u003d\u0027text/css\u0027\u003e .input, .output {border: 1px solid #888888;} .output {margin-bottom:1em;position:relative;top:-1px;} .output pre,.input pre {background-color:#EFEFEF;line-height:1.25em;margin:0;padding:0.25em;} .title {background-color:#FFFFFF;border-bottom: 1px solid #888888;font-family:arial;font-weight:bold;padding:0.25em;} \u003c/style\u003e \u003cscript type\u003d\"text/x-mathjax-config\"\u003e\n MathJax.Hub.Config({\n tex2jax: {inlineMath: [[\u0027$$$\u0027,\u0027$$$\u0027]], displayMath: [[\u0027$$$$$$\u0027,\u0027$$$$$$\u0027]]}\n });\n \u003c/script\u003e\n \u003cscript type\u003d\"text/javascript\" async\n src\u003d\"https://cdnjs.cloudflare.com/ajax/libs/mathjax/2.7.1/MathJax.js?config\u003dTeX-AMS-MML_HTMLorMML\"\u003e\n \u003c/script\u003e\n\u003cp\u003e给定一个长度为 n 的字符串 S , S\u003dS\u003cfont size\u003d1\u003e1\u003c/font\u003eS\u003cfont size\u003d1\u003e2\u003c/font\u003e...S\u003cfont size\u003d1\u003en\u003c/font\u003e,字符串中只包含数字1,2,...,9。\u003c/p\u003e\n\u003cp\u003e S 的子字符串 s[l...r] \u003d S\u003cfont size\u003d1\u003el\u003c/font\u003e S\u003cfont size\u003d1\u003el+1\u003c/font\u003e S\u003cfont size\u003d1\u003el+2\u003c/font\u003e...S\u003cfont size\u003d1\u003er\u003c/font\u003e。如果子字符串 s (最后一个元素)表达的是偶数,则称为偶数子串。\u003c/p\u003e\n\u003cp\u003e请你找出字符串 S 的偶数子串的数量。注意,只要组成子串的下标 l 和 r 不同,则认为是不同的子串。\u003c/p\u003e"}},{"title":"输入","value":{"format":"HTML","content":"\u003cp\u003e第一行输入包含一个整数 n (1≤n≤65000) —— 代表字符串长度 n 。\u003c/p\u003e\n\u003cp\u003e第二行包含长度为n的字符串 S ,字符串 S 只包含数字1,2,...,9。\u003c/p\u003e"}},{"title":"输出","value":{"format":"HTML","content":"\u003cp\u003e输出字符串 S 的偶数子串的数量\u003c/p\u003e"}},{"title":"样例","value":{"format":"HTML","content":"\u003cdiv class\u003d\"sample-test\"\u003e\n \u003cdiv class\u003d\"input\"\u003e\n \u003cdiv class\u003d\"title\"\u003e\n 输入\n \u003c/div\u003e\n \u003cpre\u003e4\n1234\n\u003c/pre\u003e\n \u003c/div\u003e\n \u003cdiv class\u003d\"output\"\u003e\n \u003cdiv class\u003d\"title\"\u003e\n 输出\n \u003c/div\u003e\n \u003cpre\u003e6\u003c/pre\u003e\n \u003c/div\u003e\n \u003cdiv class\u003d\"input\"\u003e\n \u003cdiv class\u003d\"title\"\u003e\n 输入\n \u003c/div\u003e\n \u003cpre\u003e4\n2244\n\u003c/pre\u003e\n \u003c/div\u003e\n \u003cdiv class\u003d\"output\"\u003e\n \u003cdiv class\u003d\"title\"\u003e\n 输出\n \u003c/div\u003e\n \u003cpre\u003e10\u003c/pre\u003e\n \u003c/div\u003e\n\u003c/div\u003e"}},{"title":"提示","value":{"format":"HTML","content":"\u003cp\u003e样例1中,对应偶数子串的下标如下: \u003c/p\u003e\n\u003cul\u003e \n \u003cli\u003e s[1...2]\u003c/li\u003e\n \u003cli\u003e s[2...2]\u003c/li\u003e\n \u003cli\u003e s[1...4]\u003c/li\u003e\n \u003cli\u003e s[2...4]\u003c/li\u003e\n \u003cli\u003e s[3...4]\u003c/li\u003e\n \u003cli\u003e s[4...4] \u003c/li\u003e\n\u003c/ul\u003e\n\u003cp\u003e样例2中,S的10个子串都是偶数子串。注意子串s[1...1]和子串s[2...2]都表达了数字“2”,但他们算作不同的子串。\u003c/p\u003e"}}]}