{"trustable":false,"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":"Description","value":{"format":"MD","content":"有n个人,其中一些人相互认识。\n佳爷需要将这n个人**分成若干个小队(每个小队2人)**,并使得成员之间相互认识的小队数目最大。\n但佳爷不是个随便的人,若无法将这**n个人分成两组**,且每组中的人相互不认识,那么佳爷将不会进行分队。\n请问,佳爷是否需要进行分队呢?"}},{"title":"Input","value":{"format":"MD","content":"多组输入数据。\n\n对于每组数据,第一行为两个整数n、m(1 \u0026le; n \u0026le; 200)。\n接下来m行,每行一对整数u、v,表示u和v相互认识。"}},{"title":"Output","value":{"format":"MD","content":"对于每组数据,若佳爷不需要进行分队,则输出\"No\";否则,输出最多有多少个小队的成员相互认识。"}},{"title":"Sample Input","value":{"format":"MD","content":"\u003cpre\u003e4 4\n1 2\n1 3\n1 4\n2 3\n6 5\n1 2\n1 3\n1 4\n2 5\n3 6\u003c/pre\u003e"}},{"title":"Sample Output","value":{"format":"MD","content":"\u003cpre\u003eNo\n3\u003c/pre\u003e"}}]}