{"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\"\u003eIn combinatorics a permutation of a set S with N elements is a listing of the elements of S in some order (each element occurring exactly once). There are N! permutations of a set which has N elements. For example, there are six permutations of the set {1,2,3}, namely [1,2,3], [1,3,2], [2,1,3], [2,3,1], [3,1,2], and [3,2,1]. \u003cbr\u003eBut Bob think that some permutations are more beautiful than others. Bob write some pairs of integers(Ai, Bi) to distinguish beautiful permutations from ordinary ones. A permutation is considered beautiful if and only if for some i the Ai-th element of it is Bi. We want to know how many permutations of set {1, 2, ...., N} are beautiful.\u003c/div\u003e"}},{"title":"Input","value":{"format":"HTML","content":"The first line contains an integer T indicating the number of test cases.\u003cbr\u003eThere are two integers N and M in the first line of each test case. M lines follow, the i-th line contains two integers Ai and Bi.\u003cbr\u003e\u003cbr\u003eTechnical Specification\u003cbr\u003e1. 1 \u0026lt;\u003d T \u0026lt;\u003d 50\u003cbr\u003e2. 1 \u0026lt;\u003d N \u0026lt;\u003d 17\u003cbr\u003e3. 1 \u0026lt;\u003d M \u0026lt;\u003d N*N\u003cbr\u003e4. 1 \u0026lt;\u003d Ai, Bi \u0026lt;\u003d N"}},{"title":"Output","value":{"format":"HTML","content":"For each test case, output the case number first. Then output the number of beautiful permutations in a line."}},{"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\u003e3\r\n3 2\r\n1 1\r\n2 1\r\n3 2\r\n1 1\r\n2 2\r\n4 3\r\n1 1\r\n1 2\r\n1 3\u003c/pre\u003e\u003c/td\u003e\n \u003ctd\u003e\u003cpre\u003eCase 1: 4\r\nCase 2: 3\r\nCase 3: 18\u003c/pre\u003e\u003c/td\u003e\n \u003c/tr\u003e\n\u003c/tbody\u003e\n\u003c/table\u003e\n"}}]}