{"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":"","value":{"format":"HTML","content":"\u003cscript type\u003d\u0027text/x-mathjax-config\u0027\u003eMathJax.Hub.Config({tex2jax: { inlineMath: [[\u0027$\u0027,\u0027$\u0027]] } }); \u003c/script\u003e\n\u003cscript type\u003d\u0027text/javascript\u0027 src\u003d\u0027https://cdnjs.cloudflare.com/ajax/libs/mathjax/2.7.1/MathJax.js?config\u003dTeX-AMS-MML_HTMLorMML\u0027\u003e\u003c/script\u003e\n\u003cscript type\u003d\u0027text/javascript\u0027\u003esetTimeout(function(){MathJax.Hub.Queue([\u0027Typeset\u0027, MathJax.Hub, \u0027left_view\u0027]);}, 2000);\u003c/script\u003e\n\u003cdiv class\u003d\"panel_content\"\u003e\n Give a simple directed graph with N nodes and M edges. Please tell me the maximum number of the edges you can add that the graph is still a simple directed graph. Also, after you add these edges, this graph must NOT be strongly connected. \n \u003cbr\u003e \n \u003cstrong\u003eA simple directed graph is a directed graph having no multiple edges or graph loops.\u003cbr\u003eA strongly connected digraph is a directed graph in which it is possible to reach any node starting from any other node by traversing edges in the direction(s) in which they point. \u003cbr\u003e\u003c/strong\u003e \n\u003c/div\u003e\n给定一个有向图,求最大可以增加多少条边使得这个仍然不是强连通。"}},{"title":"Input","value":{"format":"HTML","content":"The first line of date is an integer T, which is the number of the text cases. \n\u003cbr\u003eThen T cases follow, each case starts of two numbers N and M, 1\u0026lt;\u003dN\u0026lt;\u003d100000, 1\u0026lt;\u003dM\u0026lt;\u003d100000, representing the number of nodes and the number of edges, then M lines follow. Each line contains two integers x and y, means that there is a edge from x to y."}},{"title":"Output","value":{"format":"HTML","content":"For each case, you should output the maximum number of the edges you can add. \n\u003cbr\u003eIf the original graph is strongly connected, just output -1."}},{"title":"Sample Input","value":{"format":"HTML","content":"\u003cpre\u003e3\n3 3\n1 2\n2 3\n3 1\n3 3\n1 2\n2 3\n1 3\n6 6\n1 2\n2 3\n3 1\n4 5\n5 6\n6 4\u003c/pre\u003e"}},{"title":"Sample Output","value":{"format":"HTML","content":"\u003cpre\u003eCase 1: -1\nCase 2: 1\nCase 3: 15\u003c/pre\u003e"}}]}