{"trustable":true,"prependHtml":"\u003cstyle type\u003d\u0027text/css\u0027\u003e\n .input, .output {\n border: 1px solid #888888;\n }\n .output {\n margin-bottom: 1em;\n position: relative;\n top: -1px;\n }\n .output pre, .input pre {\n background-color: #EFEFEF;\n line-height: 1.25em;\n margin: 0;\n padding: 0.25em;\n }\n \u003c/style\u003e\n \u003clink rel\u003d\"stylesheet\" href\u003d\"//codeforces.org/s/96598/css/problem-statement.css\" type\u003d\"text/css\" /\u003e\n\u003cscript\u003e\n window.katexOptions \u003d {\n delimiters: [\n {left: \u0027$$$$$$\u0027, right: \u0027$$$$$$\u0027, display: true},\n {left: \u0027$$$\u0027, right: \u0027$$$\u0027, display: false},\n {left: \u0027$$\u0027, right: \u0027$$\u0027, display: true},\n {left: \u0027$\u0027, right: \u0027$\u0027, display: false}\n ]\n };\n\u003c/script\u003e\n","sections":[{"title":"","value":{"format":"HTML","content":"\u003cp\u003eĐịnh thức của ma trận \u003cspan class\u003d\"tex-span\"\u003e2 × 2\u003c/span\u003e được định nghĩa như sau:\u003c/p\u003e\u003ccenter class\u003d\"tex-equation\"\u003e\u003cimg align\u003d\"middle\" class\u003d\"tex-formula\" src\u003d\"CDN_BASE_URL/99e06c9c80235197faab4c6d30f035cc?v\u003d1718339778\" style\u003d\"max-width: 100.0%;max-height: 100.0%;\"\u003e\u003c/center\u003e\u003cp\u003eMột ma trận được gọi là \u003cspan class\u003d\"tex-font-style-it\"\u003esuy biến\u003c/span\u003e nếu định thức của nó bằng không. \u003c/p\u003e\u003cp\u003eNorm \u003cspan class\u003d\"tex-span\"\u003e||\u003ci\u003eA\u003c/i\u003e||\u003c/span\u003e của ma trận \u003cspan class\u003d\"tex-span\"\u003e\u003ci\u003eA\u003c/i\u003e\u003c/span\u003e được định nghĩa là giá trị tuyệt đối lớn nhất của các phần tử trong ma trận.\u003c/p\u003e\u003cp\u003eBạn được cho một ma trận \u003cimg align\u003d\"middle\" class\u003d\"tex-formula\" src\u003d\"CDN_BASE_URL/79df3d74013dd7b05aae75b4c303176d?v\u003d1718339778\" style\u003d\"max-width: 100.0%;max-height: 100.0%;\"\u003e. Xem xét bất kỳ ma trận suy biến nào \u003cspan class\u003d\"tex-span\"\u003e\u003ci\u003eB\u003c/i\u003e\u003c/span\u003e sao cho norm \u003cspan class\u003d\"tex-span\"\u003e||\u003ci\u003eA\u003c/i\u003e - \u003ci\u003eB\u003c/i\u003e||\u003c/span\u003e là nhỏ nhất có thể. Xác định \u003cspan class\u003d\"tex-span\"\u003e||\u003ci\u003eA\u003c/i\u003e - \u003ci\u003eB\u003c/i\u003e||\u003c/span\u003e.\u003c/p\u003e"}},{"title":"Nhập","value":{"format":"HTML","content":"\u003cp\u003eDòng đầu tiên chứa hai số nguyên \u003cspan class\u003d\"tex-span\"\u003e\u003ci\u003ea\u003c/i\u003e\u003c/span\u003e và \u003cspan class\u003d\"tex-span\"\u003e\u003ci\u003eb\u003c/i\u003e\u003c/span\u003e (\u003cspan class\u003d\"tex-span\"\u003e|\u003ci\u003ea\u003c/i\u003e|, |\u003ci\u003eb\u003c/i\u003e| ≤ 10\u003csup class\u003d\"upper-index\"\u003e9\u003c/sup\u003e\u003c/span\u003e), các phần tử của hàng đầu tiên của ma trận \u003cspan class\u003d\"tex-span\"\u003e\u003ci\u003eA\u003c/i\u003e\u003c/span\u003e. \u003c/p\u003e\u003cp\u003eDòng thứ hai chứa hai số nguyên \u003cspan class\u003d\"tex-span\"\u003e\u003ci\u003ec\u003c/i\u003e\u003c/span\u003e và \u003cspan class\u003d\"tex-span\"\u003e\u003ci\u003ed\u003c/i\u003e\u003c/span\u003e (\u003cspan class\u003d\"tex-span\"\u003e|\u003ci\u003ec\u003c/i\u003e|, |\u003ci\u003ed\u003c/i\u003e| ≤ 10\u003csup class\u003d\"upper-index\"\u003e9\u003c/sup\u003e\u003c/span\u003e) các phần tử của hàng thứ hai của ma trận \u003cspan class\u003d\"tex-span\"\u003e\u003ci\u003eA\u003c/i\u003e\u003c/span\u003e.\u003c/p\u003e"}},{"title":"Kết quả","value":{"format":"HTML","content":"\u003cp\u003eXuất ra một số thực duy nhất, giá trị nhỏ nhất có thể của \u003cspan class\u003d\"tex-span\"\u003e||\u003ci\u003eA\u003c/i\u003e - \u003ci\u003eB\u003c/i\u003e||\u003c/span\u003e. Câu trả lời của bạn được coi là chính xác nếu sai số tuyệt đối hoặc tương đối không vượt quá \u003cspan class\u003d\"tex-span\"\u003e10\u003csup class\u003d\"upper-index\"\u003e - 9\u003c/sup\u003e\u003c/span\u003e.\u003c/p\u003e"}},{"title":"Ví dụ","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\u003e1 2\n3 4\n\u003c/pre\u003e\u003c/td\u003e\n \u003ctd\u003e\u003cpre\u003e0.2000000000\n\u003c/pre\u003e\u003c/td\u003e\n \u003c/tr\u003e\n\u003c/tbody\u003e\n\u003c/table\u003e"}},{"title":"","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\u003e1 0\n0 1\n\u003c/pre\u003e\u003c/td\u003e\n \u003ctd\u003e\u003cpre\u003e0.5000000000\n\u003c/pre\u003e\u003c/td\u003e\n \u003c/tr\u003e\n\u003c/tbody\u003e\n\u003c/table\u003e"}},{"title":"Ghi chú","value":{"format":"HTML","content":"\u003cp\u003eTrong ví dụ mẫu đầu tiên, ma trận \u003cspan class\u003d\"tex-span\"\u003e\u003ci\u003eB\u003c/i\u003e\u003c/span\u003e là \u003cimg align\u003d\"middle\" class\u003d\"tex-formula\" src\u003d\"CDN_BASE_URL/4f8a8d249357ce97e1ba55a927d9d4f6?v\u003d1718339778\" style\u003d\"max-width: 100.0%;max-height: 100.0%;\"\u003e\u003c/p\u003e\u003cp\u003eTrong ví dụ mẫu thứ hai, ma trận \u003cspan class\u003d\"tex-span\"\u003e\u003ci\u003eB\u003c/i\u003e\u003c/span\u003e là \u003cimg align\u003d\"middle\" class\u003d\"tex-formula\" src\u003d\"CDN_BASE_URL/0c870b4efb22539dda2f4e9213f6bfa1?v\u003d1718339778\" style\u003d\"max-width: 100.0%;max-height: 100.0%;\"\u003e\u003c/p\u003e"}}]}