{"trustable":true,"sections":[{"title":"","value":{"format":"HTML","content":"\u003cstyle type\u003d\"text/css\"\u003e pre { text-align:left; font-family: \"Courier New\", Courier, monospace; font-size: 16px; white-space: pre; line-height:20px; text-indent: 0px; }\u003c/style\u003e\u003cdiv class\u003d\"pro_desc\"\u003e\n \u003cp\u003eAxial symmetry is so beautiful. We can find many axial symmetric objects in everyday life. Following are some axial symmetric figures. \u003c/p\u003e\n \u003cp\u003e\u003c/p\u003e\n \u003cp\u003e\u003c/p\u003e\n \u003ccenter\u003e\n \u003cimg src\u003d\"CDN_BASE_URL/3a190b6b73918ca16a65576fa82652ad?v\u003d1620299195\"\u003e\n \u003c/center\u003e\n \u003cp\u003e\u003c/p\u003e\n \u003cp\u003e\u003c/p\u003e\n \u003cp\u003eNow, you are given a simple polygon. A simple polygon is a closed polygonal chain of line segments in the plane which do not have points in common other than the common vertices of pairs of consecutive segments.\u003c/p\u003e\n \u003cp\u003eTo simplify the problem, the given simple polygon in this problem is special. All edges of the given polygon parallel to either X-axis or Y-axis. Your task is to examine whether the given polygon is axial symmetric.\u003c/p\u003e\n\u003c/div\u003e"}},{"title":"Input","value":{"format":"HTML","content":"\u003cdiv class\u003d\"pro_desc\"\u003e\n \u003cp\u003eThe first line of the input contains an integer T(T≤50), indicating the number of test cases. Each case begins with one integer n(10≤n≤500), the number of points. The next n lines indicate the points of the polygon, each with two integers x(-100,000≤x≤100,000) and y(-100,000≤y≤100,000). The points would be given either clockwise or counterclockwise.\u003c/p\u003e\n\u003c/div\u003e"}},{"title":"Output","value":{"format":"HTML","content":"\u003cdiv class\u003d\"pro_desc\"\u003e\n \u003cp\u003eFor each test case, print a line containing the test case number (beginning with 1) and if the polygon is axial symmetric, please output “YES”, or you should output “NO”.\u003c/p\u003e\n\u003c/div\u003e"}},{"title":"Sample Input","value":{"format":"HTML","content":"\u003cpre\u003e2\r\n4\r\n0 0\r\n0 1\r\n1 1\r\n1 0\r\n6\r\n0 0\r\n4 0\r\n4 2\r\n1 2\r\n1 4\r\n0 4\r\n\u003c/pre\u003e"}},{"title":"Sample Output","value":{"format":"HTML","content":"\u003cpre\u003eCase 1: YES\r\nCase 2: NO\r\n\u003c/pre\u003e"}}]}