{"trustable":false,"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\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 type\u003d\"text/javascript\" async src\u003d\"https://mathjax.codeforces.org/MathJax.js?config\u003dTeX-AMS_HTML-full\"\u003e\u003c/script\u003e","sections":[{"title":"","value":{"format":"HTML","content":"For a positive integer \u003ci\u003en\u003c/i\u003e let\u0027s define a function \u003ci\u003ef\u003c/i\u003e:\u003cbr\u003e\u003cbr\u003e\n\n\u003ci\u003ef\u003c/i\u003e(\u003ci\u003en\u003c/i\u003e) \u003d - 1 + 2 - 3 + .. + ( - 1 )\u003csup\u003e\u003ci\u003en\u003c/i\u003e\u003c/sup\u003e\u003ci\u003en\u003c/i\u003e\u003cbr\u003e\u003cbr\u003e\n\nYour task is to calculate \u003ci\u003ef\u003c/i\u003e(\u003ci\u003en\u003c/i\u003e) for a given integer \u003ci\u003en\u003c/i\u003e."}},{"title":"Input","value":{"format":"HTML","content":"The single line contains the positive integer \u003ci\u003en\u003c/i\u003e (1 ≤ \u003ci\u003en\u003c/i\u003e ≤ 10\u003csup\u003e15\u003c/sup\u003e)."}},{"title":"Output","value":{"format":"HTML","content":"Print \u003ci\u003ef\u003c/i\u003e(\u003ci\u003en\u003c/i\u003e) in a single line."}},{"title":"Examples","value":{"format":"HTML","content":"\u003ctable border\u003d\"1px solid\" width\u003d\"100%\" cellpadding\u003d\"4px\" cellspacing\u003d\"0px\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003cth width\u003d\"50%\"\u003eSample Input 1\u003c/th\u003e\n \u003cth width\u003d\"50%\"\u003eSample Output 1\u003c/th\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign\u003d\"top\"\u003e\u003ccode\u003e\n4\u003cbr\u003e\n \u003cbr\u003e\u003c/code\u003e\u003c/td\u003e\n \u003ctd valign\u003d\"top\"\u003e\u003ccode\u003e\n2\u003cbr\u003e\n \u003cbr\u003e\u003c/code\u003e\u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\u003cbr\u003e\u003cbr\u003e\n\n\u003ctable border\u003d\"1px solid\" width\u003d\"100%\" cellpadding\u003d\"4px\" cellspacing\u003d\"0px\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003cth width\u003d\"50%\"\u003eSample Input 2\u003c/th\u003e\n \u003cth width\u003d\"50%\"\u003eSample Output 2\u003c/th\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign\u003d\"top\"\u003e\u003ccode\u003e\n5\u003cbr\u003e\n \u003cbr\u003e\u003c/code\u003e\u003c/td\u003e\n \u003ctd valign\u003d\"top\"\u003e\u003ccode\u003e\n-3\u003cbr\u003e\n \u003cbr\u003e\u003c/code\u003e\u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e"}},{"title":"Note","value":{"format":"HTML","content":"\u003ci\u003ef\u003c/i\u003e(4) \u003d - 1 + 2 - 3 + 4 \u003d 2\u003cbr\u003e\n\u003ci\u003ef\u003c/i\u003e(5) \u003d - 1 + 2 - 3 + 4 - 5 \u003d - 3"}}]}