String Game - Palindrome Checker

You are given a series of operations that manipulate a string. There are three types of operations:

• 1 x: Append the character x to the end of the string.
• 2: Remove the last character of the string if it exists.
• 3: Check if the current string is a palindrome and output the result.

A string s is a palindrome if it reads the same forwards and backwards. Formally, a string s of length n is a palindrome if \( s[i] = s[n-i+1] \) for all \( 1 \le i \le n \). Note that the empty string is considered a palindrome.

Your task is to simulate these operations sequentially and output the result of each type 3 operation.

inputFormat

The first line of input contains an integer N representing the number of operations.

Each of the next N lines contains a single operation in one of the following formats:

• 1 x (where x is a lowercase English letter)
• 2
• 3

outputFormat

For each operation of type 3, output a line containing YES if the current string is a palindrome, or NO if it is not.

## sample

4
1 a
1 b
1 a
3

YES

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