{"raw_statement":[{"iden":"statement","content":"*Palindrome* is a word that looks the same when you read it from the beginning and from the end. For example \"kayak\", \"level\". The same is with numbers: $909$, $1221$, $12321$ are palindromes. For a given list of numbers, please print how many of them are palindromes.\n\nIn the first line of input we have a single number $1 <= n <= 100$. In the next line there follows $n$ positive numbers, not bigger than $10^(50)$.\n\nPrint a single number: how many among input numbers are palindromes?\n\n"},{"iden":"input","content":"In the first line of input we have a single number $1 <= n <= 100$. In the next line there follows $n$ positive numbers, not bigger than $10^(50)$."},{"iden":"output","content":"Print a single number: how many among input numbers are palindromes?"}],"translated_statement":null,"sample_group":[],"show_order":[],"formal_statement":"**Definitions**  \nLet $ n \\in \\mathbb{Z} $, $ n \\geq 2 $.  \nLet $ a, b \\in \\Sigma^n $, where $ \\Sigma = \\{ \\text{a}, \\text{b}, \\dots, \\text{z} \\} $, be two strings of length $ n $.  \n\n**Constraints**  \n1. $ 2 \\leq n \\leq 10^5 $  \n2. All characters in $ a $ and $ b $ are lowercase English letters.  \n3. The operation consists of selecting two distinct indices $ x, y \\in \\{1, \\dots, n\\} $, $ x \\ne y $, and swapping $ a_x \\leftrightarrow a_y $ and $ b_x \\leftrightarrow b_y $.  \n\n**Objective**  \nDetermine whether there exists a pair $ (x, y) $, $ x \\ne y $, such that after the swap, the resulting string $ a' $ is lexicographically greater than $ b' $, i.e.,  \n$$\na' >_{\\text{lex}} b'\n$$  \nIf such a pair exists, output $ \\text{YES} $ followed by $ x, y $; otherwise, output $ \\text{NO} $.","simple_statement":"You are given two strings a and b of length n.  \nYou must swap exactly one pair of positions (x, y) where x ≠ y: swap a[x] with a[y] and b[x] with b[y].  \nAfter the swap, check if string a becomes lexicographically greater than string b.  \n\nIf possible, print \"YES\" and then x and y (1-indexed).  \nIf impossible, print \"NO\".","has_page_source":false}