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$ curl repovive.com/contests/14/problems/E

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Palindromic Not - Repovive Standard Round 5 | Repovive | Repovive

14E. Palindromic Not

2500 pts1s256 MB

You are given two binary strings $S$ and $T$ , both of length $n$ .

In one operation, you choose two indices $l$ and $r$ such that $1 \le l < r \le n$ , and the substring $S_l S_{l+1} \ldots S_r$ is a palindrome. Then you invert every bit in this substring. In other words, every $0$ becomes $1$ , and every $1$ becomes $0$ .

You have to determine whether it is possible to transform $S$ into $T$ .

If it is possible, output any sequence of at most $n+10$ operations that transforms $S$ into $T$ .

Constraints

$1 \le t \le 100$
$1 \le n \le 2000$
$S$ and $T$ are binary strings of length $n$

Input

The first line contains an integer $t$ , the number of test cases.

Then the test cases are given in the following format:

t

\left. \begin{array}{l} n \\ S \\ T \end{array} \right\} \times t

Output

For each test case, if it is impossible to transform $S$ into $T$ , output:

\texttt{No}

Otherwise, output:

\begin{array}{l} \texttt{Yes} \\ m \\ l_1 \quad r_1 \\ l_2 \quad r_2 \\ \vdots \\ l_m \quad r_m \end{array}

Here $m$ is the number of operations, and it must satisfy $0 \le m \le n+10$ . For every $i$ , the segment $[l_i,r_i]$ must be valid at the moment when the $i$ -th operation is applied.

The words Yes and No must be printed exactly in this form. If there are several valid answers, output any of them.

Samples

Input

Case 1

5
01010
10101

Explanation

The chosen substring from positions 1 to 5 is 01010, which is a palindrome. After inverting it, the string becomes 10101, so it is equal to the target string.

Output

Yes
1
1 5

Input

Case 1

3
000
010

Case 2

4
0101
0000

Case 3

5
11100
00111

Explanation

Case 1

It is impossible.

Case 2

0101 becomes 1011, then 1000, then 1111, and finally 0000.

Case 3

11100 becomes 00000, then 00111.

Output

Case 1

No

Case 2

Case 3

Yes
2
1 3
3 5

You are given two binary strings $S$ and $T$ , both of length $n$ .

You have to determine whether it is possible to transform $S$ into $T$ .

If it is possible, output any sequence of at most $n+10$ operations that transforms $S$ into $T$ .

$1 \le t \le 100$
$1 \le n \le 2000$
$S$ and $T$ are binary strings of length $n$

The first line contains an integer $t$ , the number of test cases.

Then the test cases are given in the following format:

t

\left. \begin{array}{l} n \\ S \\ T \end{array} \right\} \times t

For each test case, if it is impossible to transform $S$ into $T$ , output:

\texttt{No}

Otherwise, output:

\begin{array}{l} \texttt{Yes} \\ m \\ l_1 \quad r_1 \\ l_2 \quad r_2 \\ \vdots \\ l_m \quad r_m \end{array}

Here $m$ is the number of operations, and it must satisfy $0 \le m \le n+10$ . For every $i$ , the segment $[l_i,r_i]$ must be valid at the moment when the $i$ -th operation is applied.

The words Yes and No must be printed exactly in this form. If there are several valid answers, output any of them.

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14E. Palindromic Not

Constraints

Input

Output

Samples

14E. Palindromic Not

Constraints

Input

Output

Samples