Swapping positions

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Ad-Hoc, Algorithms, Basic Programming, Basics of Implementation, Easy, Implementation

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Problem

You are given two strings $s$ and $t$ of length $n$ . You can select any two positions (can be from the same or different strings) and swap the characters at those two positions. You have to perform this operation exactly once in such a way that there exists maximum one position $i$ $(1 \le i \le n)$ such that $s_i !=t_i$ .
Determine whether it is possible to perform the operation such that the given condition holds or not.

Input format

First line: A single integer $T$ that denotes the number of test cases
For each test case:
- First line: An integer $n$
- Next two lines: Strings $s$ and $t$ respectively

Output format

For each test case, print YES if a valid operation exists otherwise print NO in a single line.

Input constraints

$1 \le T \le 50$
$1 \le n \le 10^3$
Both the strings $s$ and $t$ contain only lowercase English alphabets

Sample Input

2
8
mrxismrx
mryismry
8
iamnomrx
iamdamry

Sample Output

YES
NO

Time Limit: 2

Memory Limit: 256

Source Limit:

Explanation

In the first test case, we can get a valid result by swapping the characters $s_3$ and $t_8$ (1 based indexing).

Contributers:

Tarango Khan

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