{"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\"\u003eA palindrome is a symmetrical string, that is, a string read identically from left to right as well as from right to left. You are to write a program which, given a string, determines the minimal number of characters to be inserted into the string in order to obtain a palindrome. \u003cbr\u003e\u003cbr\u003eAs an example, by inserting 2 characters, the string \"Ab3bd\" can be transformed into a palindrome (\"dAb3bAd\" or \"Adb3bdA\"). However, inserting fewer than 2 characters does not produce a palindrome. \u003c/div\u003e"}},{"title":"Input","value":{"format":"HTML","content":"Your program is to read from standard input. The first line contains one integer: the length of the input string N, 3 \u0026lt;\u003d N \u0026lt;\u003d 5000. The second line contains one string with length N. The string is formed from uppercase letters from \u0027A\u0027 to \u0027Z\u0027, lowercase letters from \u0027a\u0027 to \u0027z\u0027 and digits from \u00270\u0027 to \u00279\u0027. Uppercase and lowercase letters are to be considered distinct.\u003cbr\u003e "}},{"title":"Output","value":{"format":"HTML","content":"Your program is to write to standard output. The first line contains one integer, which is the desired minimal number.\u003cbr\u003e"}},{"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\u003e5\r\nAb3bd\r\n\u003c/pre\u003e\u003c/td\u003e\n \u003ctd\u003e\u003cpre\u003e2\r\n\u003c/pre\u003e\u003c/td\u003e\n \u003c/tr\u003e\n\u003c/tbody\u003e\n\u003c/table\u003e\n"}}]}