{"raw_statement":[{"iden":"problem statement","content":"Given is a string $S$ consisting of lowercase English letters. Determine whether adding some number of `a`'s (possibly zero) at the beginning of $S$ can make it a palindrome.\nHere, a string of length $N$, $A=A_1A_2\\ldots A_N$, is said to be a palindrome when $A_i=A_{N+1-i}$ for every $1\\leq i\\leq N$."},{"iden":"constraints","content":"*   $1 \\leq \\lvert S \\rvert \\leq 10^6$\n*   $S$ consists of lowercase English letters."},{"iden":"input","content":"Input is given from Standard Input in the following format:\n\n$S$"},{"iden":"sample input 1","content":"kasaka"},{"iden":"sample output 1","content":"Yes\n\nBy adding one `a` at the beginning of `kasaka`, we have `akasaka`, which is a palindrome, so `Yes` should be printed."},{"iden":"sample input 2","content":"atcoder"},{"iden":"sample output 2","content":"No\n\nAdding any number of `a`'s at the beginning of `atcoder` does not make it a palindrome."},{"iden":"sample input 3","content":"php"},{"iden":"sample output 3","content":"Yes\n\n`php` itself is a palindrome. Adding zero `a`'s at the beginning of $S$ is allowed, so `Yes` should be printed."}],"translated_statement":null,"sample_group":[],"show_order":["default"],"formal_statement":null,"simple_statement":null,"has_page_source":true}