{"trustable":true,"prependHtml":"\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 async src\u003d\"https://mathjax.codeforces.org/MathJax.js?config\u003dTeX-AMS-MML_HTMLorMML\" type\u003d\"text/javascript\"\u003e\u003c/script\u003e","sections":[{"title":"","value":{"format":"HTML","content":"\u003cdiv class\u003d\"panel_content\"\u003eThere are a group of students. Some of them may know each other, while others don\u0027t. For example, A and B know each other, B and C know each other. But this may not imply that A and C know each other.\u003cbr\u003e\u003cbr\u003eNow you are given all pairs of students who know each other. Your task is to divide the students into two groups so that any two students in the same group don\u0027t know each other.If this goal can be achieved, then arrange them into double rooms. Remember, only paris appearing in the previous given set can live in the same room, which means only known students can live in the same room.\u003cbr\u003e\u003cbr\u003eCalculate the maximum number of pairs that can be arranged into these double rooms.\u003cbr\u003e\u003c/div\u003e"}},{"title":"Input","value":{"format":"HTML","content":"For each data set:\u003cbr\u003eThe first line gives two integers, n and m(1\u0026lt;n\u0026lt;\u003d200), indicating there are n students and m pairs of students who know each other. The next m lines give such pairs.\u003cbr\u003e\u003cbr\u003eProceed to the end of file.\u003cbr\u003e\u003cbr\u003e"}},{"title":"Output","value":{"format":"HTML","content":"If these students cannot be divided into two groups, print \"No\". Otherwise, print the maximum number of pairs that can be arranged in those rooms.\u003cbr\u003e"}},{"title":"Sample","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 4\r\n1 2\r\n1 3\r\n1 4\r\n2 3\r\n6 5\r\n1 2\r\n1 3\r\n1 4\r\n2 5\r\n3 6\u003c/pre\u003e\u003c/td\u003e\n \u003ctd\u003e\u003cpre\u003eNo\r\n3\u003c/pre\u003e\u003c/td\u003e\n \u003c/tr\u003e\n\u003c/tbody\u003e\n\u003c/table\u003e\n"}}]}