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Palindromifier

1000ms 262144K

Description:

Ringo found a string $$$s$$$ of length $$$n$$$ in his yellow submarine. The string contains only lowercase letters from the English alphabet. As Ringo and his friends love palindromes, he would like to turn the string $$$s$$$ into a palindrome by applying two types of operations to the string.

The first operation allows him to choose $$$i$$$ ($$$2 \le i \le n-1$$$) and to append the substring $$$s_2s_3 \ldots s_i$$$ ($$$i - 1$$$ characters) reversed to the front of $$$s$$$.

The second operation allows him to choose $$$i$$$ ($$$2 \le i \le n-1$$$) and to append the substring $$$s_i s_{i + 1}\ldots s_{n - 1}$$$ ($$$n - i$$$ characters) reversed to the end of $$$s$$$.

Note that characters in the string in this problem are indexed from $$$1$$$.

For example suppose $$$s=$$$abcdef. If he performs the first operation with $$$i=3$$$ then he appends cb to the front of $$$s$$$ and the result will be cbabcdef. Performing the second operation on the resulted string with $$$i=5$$$ will yield cbabcdefedc.

Your task is to help Ringo make the entire string a palindrome by applying any of the two operations (in total) at most $$$30$$$ times. The length of the resulting palindrome must not exceed $$$10^6$$$

It is guaranteed that under these constraints there always is a solution. Also note you do not have to minimize neither the number of operations applied, nor the length of the resulting string, but they have to fit into the constraints.

Input:

The only line contains the string $$$S$$$ ($$$3 \le |s| \le 10^5$$$) of lowercase letters from the English alphabet.

Output:

The first line should contain $$$k$$$ ($$$0\le k \le 30$$$)  — the number of operations performed.

Each of the following $$$k$$$ lines should describe an operation in form L i or R i. $$$L$$$ represents the first operation, $$$R$$$ represents the second operation, $$$i$$$ represents the index chosen.

The length of the resulting palindrome must not exceed $$$10^6$$$.

Sample Input:

abac

Sample Output:

2
R 2
R 5

Sample Input:

acccc

Sample Output:

2
L 4
L 2

Sample Input:

hannah

Sample Output:

0

Note:

For the first example the following operations are performed:

abac $$$\to$$$ abacab $$$\to$$$ abacaba

The second sample performs the following operations: acccc $$$\to$$$ cccacccc $$$\to$$$ ccccacccc

The third example is already a palindrome so no operations are required.

Informação

Codeforces

Provedor Codeforces

Código CF1421C

Tags

constructive algorithmsstrings

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Datas 09/05/2023 10:06:59

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