{"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":"\u003cp\u003e一个 \u003cspan class\u003d\"tex-font-style-it\"\u003ebracket sequence\u003c/span\u003e是由\"\u003cspan class\u003d\"tex-font-style-tt\"\u003e(\u003c/span\u003e\", \"\u003cspan class\u003d\"tex-font-style-tt\"\u003e)\u003c/span\u003e\", \"\u003cspan class\u003d\"tex-font-style-tt\"\u003e[\u003c/span\u003e\" 和 \"\u003cspan class\u003d\"tex-font-style-tt\"\u003e]\u003c/span\u003e\"组成的字符串(没有其他字符).\u003c/p\u003e\n\u003cp\u003e一个 \u003cspan class\u003d\"tex-font-style-it\"\u003ecorrect bracket sequence\u003c/span\u003e是在字符串中加入 \"\u003cspan class\u003d\"tex-font-style-tt\"\u003e1\u003c/span\u003e\" 和 \"\u003cspan class\u003d\"tex-font-style-tt\"\u003e+\u003c/span\u003e\"之后成为一个合法的数学算式的字符串. For example, bracket sequences \"\u003cspan class\u003d\"tex-font-style-tt\"\u003e()[]\u003c/span\u003e\", \"\u003cspan class\u003d\"tex-font-style-tt\"\u003e([])\u003c/span\u003e\" are correct (the resulting expressions are: \"\u003cspan class\u003d\"tex-font-style-tt\"\u003e(1)+[1]\u003c/span\u003e\", \"\u003cspan class\u003d\"tex-font-style-tt\"\u003e([1+1]+1)\u003c/span\u003e\"), and \"\u003cspan class\u003d\"tex-font-style-tt\"\u003e](\u003c/span\u003e\" and \"\u003cspan class\u003d\"tex-font-style-tt\"\u003e[\u003c/span\u003e\" are not. \u003cspan class\u003d\"tex-font-style-bf\"\u003eThe empty string is a correct bracket sequence by definition.\u003c/span\u003e\u003c/p\u003e\n\u003cp\u003e一个 字符串的\u003cspan class\u003d\"tex-font-style-it\"\u003esubstring\u003c/span\u003e 指的是将这个字符串开头或末尾的若干个字符删去后所组成的字符串,例如()()的substring可以是)(,而不是)).\u003c/p\u003e\n\u003cp\u003e现给出一个bracket sequence(他很可能不是correct的). 找出他的correct substring中含有‘[’最多的correct substring.\u003c/p\u003e"}},{"title":"Input","value":{"format":"HTML","content":"\u003cp\u003eThe first and the only line contains the bracket sequence as a string, consisting only of characters \"\u003cspan class\u003d\"tex-font-style-tt\"\u003e(\u003c/span\u003e\", \"\u003cspan class\u003d\"tex-font-style-tt\"\u003e)\u003c/span\u003e\", \"\u003cspan class\u003d\"tex-font-style-tt\"\u003e[\u003c/span\u003e\" and \"\u003cspan class\u003d\"tex-font-style-tt\"\u003e]\u003c/span\u003e\". It is guaranteed that the string is non-empty and its length doesn\u0027t exceed \u003cspan class\u003d\"tex-span\"\u003e10\u003csup class\u003d\"upper-index\"\u003e5\u003c/sup\u003e\u003c/span\u003e characters.\u003c/p\u003e"}},{"title":"Output","value":{"format":"HTML","content":"\u003cp\u003e第一行输出最长的correct substring中 «\u003cspan class\u003d\"tex-font-style-tt\"\u003e[\u003c/span\u003e» 的个数. 第二行输出这个最长的correct substring. I(可能有多个符合要求的答案,只需输出其中一个).\u003c/p\u003e"}},{"title":"Sample 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\u003e([])\n\u003c/pre\u003e\u003c/td\u003e\n \u003ctd\u003e\u003cpre\u003e1\n([])\n\u003c/pre\u003e\u003c/td\u003e\n \u003c/tr\u003e\n\u003c/tbody\u003e\n\u003c/table\u003e\n"}},{"title":"Sample 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\u003e(((\n\u003c/pre\u003e\u003c/td\u003e\n \u003ctd\u003e\u003cpre\u003e0\n\n\u003c/pre\u003e\u003c/td\u003e\n \u003c/tr\u003e\n\u003c/tbody\u003e\n\u003c/table\u003e\n"}}]}