{"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\"\u003eBecause of Covid-19, Kanade needs to report every time when entering and leaving school. Now you want to check if Kanade\u0027s reports on a certain day are correct.\u003cbr\u003e\u003cbr\u003eA sequence of reports is correct if and only if there does not exist two consecutive and same reports.\u003c/div\u003e"}},{"title":"Input","value":{"format":"HTML","content":"There are $T$ test cases in this problem.\u003cbr\u003e\u003cbr\u003eThe first line has one integer $T$.\u003cbr\u003e\u003cbr\u003eFor every test case:\u003cbr\u003e\u003cbr\u003eThe first line has one integer $n$ which denotes the number of times Kanade reported on a certain day.\u003cbr\u003e\u003cbr\u003eThe second line has $n$ integers $a_1,a_2,a_3,\\cdots,a_n$, $a_i$ denotes the type of the $i$-th report. $a_i\u003d0$ denotes a leaving school report and $a_i\u003d1$ denotes an entering school report.\u003cbr\u003e\u003cbr\u003e$1\\leq T\\leq 100$\u003cbr\u003e\u003cbr\u003e$3\\leq n\\leq 50$\u003cbr\u003e\u003cbr\u003e$0\\leq a_i\\leq 1$"}},{"title":"Output","value":{"format":"HTML","content":"For every test case, output ``YES\u0027\u0027 if Kanade\u0027s reports are correct, otherwise output ``NO\u0027\u0027 (without quotes)"}},{"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\u003e4\r\n3\r\n1 1 1\r\n3\r\n1 0 1\r\n5\r\n0 1 0 1 0\r\n4\r\n1 0 1 1\u003c/pre\u003e\u003c/td\u003e\n \u003ctd\u003e\u003cpre\u003eNO\r\nYES\r\nYES\r\nNO\u003c/pre\u003e\u003c/td\u003e\n \u003c/tr\u003e\n\u003c/tbody\u003e\n\u003c/table\u003e\n"}}]}