A. Palindrome

Codeforces

IDCF10241A

Time1000ms

Memory256MB

Difficulty—

English · Original

Formal · Original

*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. 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 $10^(50)$. Print a single number: how many among input numbers are palindromes? ## Input 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 $10^(50)$. ## Output Print a single number: how many among input numbers are palindromes? [samples]

**Definitions** Let $ n \in \mathbb{Z} $, $ n \geq 2 $. Let $ a, b \in \Sigma^n $, where $ \Sigma = \{ \text{a}, \text{b}, \dots, \text{z} \} $, be two strings of length $ n $. **Constraints** 1. $ 2 \leq n \leq 10^5 $ 2. All characters in $ a $ and $ b $ are lowercase English letters. 3. 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 $. **Objective** Determine 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., $$ a' >_{\text{lex}} b' $$ If such a pair exists, output $ \text{YES} $ followed by $ x, y $; otherwise, output $ \text{NO} $.

API Response (JSON)

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